by Rashida Adjani and Biodun Iginla, BBC News

Territory north of the Nafusa Mountains is currently an active sector of the front line

The campaign group Human Rights Watch has accused rebels in Libya of looting, arson and the abuse of civilians.

Observers from the New York-based group say they have witnessed some incidents themselves, and have interviewed witnesses to others in territory recently seized by rebels.

A rebel spokesman talking to reporters in Brussels has denied the allegations.

Accusations of abuse by both sides have circulated since the rebellion against Col Muammar Gaddafi began in February.

The latest allegations focus on four towns seized by rebels in the west of the country in the last month: al-Awaniya, Rayayinah, Zawiyat al-Bagul and al-Qawalish.

"The rebel conduct was disturbing," said Fred Abrahams, Human Rights Watch (HRW) research supervisor.

"We documented fairly widespread looting of homes and shops, the burning of some homes of suspected Gaddafi supporters and - most disturbingly - the vandalisation of three medical clinics [and] local small hospitals, including the theft of some of the medical equipment."

He said the Libyan government had committed more serious crimes, but that did not excuse the behaviour of the rebels.

"Our aim is to hold all combatants, all militaries - whether they're organised and states and governments or rebels groups - to the same standards, and it's very much also a warning shot across the bow, because of these other areas they are approaching. We're deeply worried about how they might behave and treat civilians in those areas."

A senior rebel leader has refuted the Human Rights Watch claims.

"This is not the case in the liberated areas," rebel spokesman Mahmud Jibril told reporters in Brussels.

In the latest news from this sector of the front line, the BBC's World Affairs Editor, John Simpson, reports that a counter-attack is underway by forces loyal to Colonel Muammar Gaddafi.

When pro-Gaddafi forces probed rebel positions at al-Qawalish, the rebels took to their vehicles and fled.

The rebels' early gains came in the East of Libya. Then their struggle against the army became deadlocked, despite a bombing campaign by Nato warplanes against pro-Gaddafi forces.

In recent weeks attention shifted to the west of the country, when opposition fighters based in the Nafusa Mountains (or Jebel Nafusa) seized territory bringing them to within 90km (55 miles) of Tripoli.

It is these gains the latest counter-attack aims to reverse.

by Natalie de Vallieres and Biodun Iginla, BBC News

Muammar Gaddafi is holding to Tripoli and other parts of western Libya

France says it has had contacts with envoys from Muammar Gaddafi who say the Libyan leader is "prepared to leave".

"The Libyan regime is sending messengers everywhere, to Turkey, to New York, to Paris" offering to discuss Col Gaddafi's exit, French Foreign Minister Alain Juppe told French radio.

But he added that such contacts did not constitute negotiations.

France played a key role in launching Nato-led strikes in Libya, under a UN-mandated mission to protect civilians.

Mr Juppe told France Info radio on Tuesday: "We are receiving emissaries who are telling us: 'Gaddafi is prepared to leave. Let's discuss it.'

"There are contacts but it's not a negotiation proper at this stage."

Mr Juppe did not say who the emissaries were.

French foreign ministry spokesman Bernard Valero said: "These are emissaries who say they are coming in the name of Gaddafi. What is important is that we send them the same message and stay in close contact with our allies on this."

The comments come as the French parliament debated the continuation of air strikes over Libya, four months into the campaign.

Prime Minister Francois Fillon told the assembly that a political solution was "beginning to take shape".

Hugh Schofield in Paris says that although this may turn out to be overblown, the French - who are prime movers in the Libya campaign - seem to be showing the first signs that it could be heading towards a conclusion.

Rebels are holding eastern Libya and pockets in the west, but have so far not made decisive moves towards the capital Tripoli, where Col Gaddafi remains entrenched.

France and other coalition countries have insisted that the Libyan leader must stand down for hostilities to end.

by Biodun Iginla and Maria Ogryzlo, BBC News

Russia has strongly criticised France for dropping weapons to Libyan rebels and demanded an explanation from Paris.

"If this is confirmed, it is a very crude violation of UN Security Council resolution 1970," Foreign Minister Sergei Lavrov said.

The African Union has also criticised the move, saying it risks causing a "Somalia-sation" of Libya.

The French military says it has dropped arms to Berber tribal fighters in the mountains south-west of the capital.

Mr Lavrov said Russia had formally requested information from France about the move, to check that it "corresponds with reality".

Moscow abstained from the UN Security Council vote in March that authorised an international mission in Libya to protect civilians.

Russia and China have both criticised the Nato campaign in recent weeks, saying it had gone beyond the remit of UN resolution 1973.

Another resolution, 1970, had imposed an arms embargo on Libya.

But US and UK officials have argued that resolution 1973 could nonetheless allow weapons to be supplied to rebels fighting to topple Libyan leader Muammar Gaddafi.

by Biodun Iginla, BBC News

Muammar Gaddafi is accused of personally ordering attacks on civilians

The International Criminal Court has issued an arrest warrant for Libyan leader Col Muammar Gaddafi, accusing him of crimes against humanity.

The court had grounds to believe he had ordered attacks on civilians during Libya's four-month uprising, it said.

The Hague-based court also issued warrants for two of Col Gaddafi's top aides - his son Saif al-Islam and intelligence chief Abdullah al-Sanussi.

Thousands of people are believed to have been killed in the conflict.

Anti-Gaddafi forces said on Monday they had launched a new push towards Tripoli, with heavy fighting near the strategic town of Bir al-Ghanam, to the south-west of capital.

The rebel defence minister told the BBC that forces opposed to Col Gaddafi may also make a move on the capital from the east.

The ICC arrest warrants refer to early weeks of the uprising, from 15 February until "at least 28 February".

The statement, read out by presiding judge Sanji Monageng, said there were "reasonable grounds to believe" that the three men were "criminally responsible" for the murder and persecution of civilians.

As the "recognised and undisputed leader of Libya", said the court, Col Gaddafi had "absolute, ultimate and unquestioned control" over the state.

He introduced a state policy "aimed at deterring and quelling by any means, including by the use of force, the demonstrations of civilians against the regime", the court alleged.

The warrant says that while Saif al-Islam Gaddafi holds no official position in Libya, he is "the most influential person" in Col Gaddafi's inner circle.

Mr Sanussi, said the court, had "indirectly instructed the troops to attack civilians demonstrating" in Benghazi, the city that has become the rebels' stronghold.

The BBC's Andrew Harding in Misrata said there was celebratory gunfire on the streets of the besieged city as the news emerged.

"We are extremely happy that the whole world has united in prosecuting Gaddafi for the crimes he has committed," rebel council spokesman Jalal al-Galal told Reuters news agency from the rebel stronghold Benghazi. "The people feel vindicated by such a response."

On the military front, meanwhile, the rebels have advanced some six miles (10km) towards Tripoli in the past 24 hours, says the BBC's Mark Doyle on the front line about 40 miles south-west of the capital.

The fighting is taking place on a plain of rock and sand between Bir al-Ghanem and Bir Ayyad a few miles to the south, with shells whistling overhead in both directions and plumes of smoke and sand rising into the air, he says.

The rebels seem better armed in this strategic area than elsewhere in the country, adds our correspondent, who saw several pick-up trucks full of rebel soldiers - in clean uniforms and new-looking rocket launchers and rifles - heading for the front line.

The warrants had been requested by chief ICC prosecutor Luis Moreno-Ocampo in May. He has said Col Gaddafi must be arrested in order to protect civilians.

Continue reading the main story

Analysis

Andrew Harding BBC News, Misrata

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There were celebrations across Misrata today, with car horns beeping, and a lot of gunfire in the air as people greeted the news from the ICC.

This still besieged city has suffered a great deal at the hands of Col Gaddafi's forces, which have pounded the city itself and killed many civilians.

A lot of people I've been speaking to say they believe Col Gaddafi should face justice in the Hague. But, when pressed, many people also say that if his internal or external exile or house arrest would end this war quicker, they'd be happy to accept that.

• Misrata: 100 days of bombing

But the Libyan authorities have previously said they do not recognise the court and are not concerned by the threat of a warrant.

On Sunday, government spokesman Moussa Ibrahim said the court was overly preoccupied with pursuing African leaders and had "no legitimacy whatsoever".

The ICC announcement came as the international air operation in Libya, aimed at protecting civilians, enters its 100th day.

It was welcomed by Nato Secretary-General Anders Fogh Rasmussen, who said the court's decision highlighted the increasing isolation of the Libyan regime.

"It reinforces the reason for Nato's mission to protect the Libyan people from Gaddafi's forces," said Mr Fogh Rasmussen in Brussels.

UK Foreign Secretary William Hague said the court's decision further demonstrated "why Gaddafi has lost all legitimacy and why he should go immediately".

Mr Hague called on people within the Libyan regime to abandon the leader and said those responsible for "atrocities" must be held to account.

French President Nicolas Sarkozy echoed those sentiments, saying of the Libyan leader: "After 41 years of dictatorship, it is perhaps time to stop, for him to leave power."

by Biodun Iginla and Melissa Gruz, BBC News

Some Obama allies in Congress accused Republicans of playing political games with national security

The US House of Representatives has voted against a resolution giving President Barack Obama authority to order US operations in Libya.

However, the House on Friday also voted down a Republican effort to cut off money for the Libya conflict.

US backing for the Nato operation in Libya has drawn criticism from many in Congress in recent weeks.

Opponents say the three-month-old operation is in breach of legislation requiring the backing of Congress.

"The president has operated in what we now know is called the zone of twilight as to whether or not he even needs our approval," Republican Representative Tom Rooney of Florida said. "So what are we left with?"

Mr Obama says he does not need additional congressional approval, as US forces are simply supporting Nato.

His allies in Congress urged members of the House to vote for the resolution authorising the conflict.

"A sudden withdrawal of American support for the mission would strengthen Gaddafi's hand and increase his confidence that he can wait out the rebellion against his rule," Democratic Whip Steny Hoyer of Maryland said on the House floor.

"It would put civilian lives at risk... I urge my colleagues: protect our valuable alliances and the principles of human rights that they safeguard."

Under the terms of the resolution, the US would have been allowed to conduct "limited" operations for one year in Libya.

The introduction of ground troops would have been banned.

Analysts suggest Democrats angry at Mr Obama's continued commitment of resources to the Libya campaign could refuse to vote against the resolution, delivering another rebuke to the president.

The disagreement between Congress and the White House stems from a Vietnam War-era law, the War Powers resolution, intended to constrain the president's ability to wage military conflict with congressional approval.

Under the US constitution only Congress can declare war, and the 1973 War Powers resolution requires that, without such a declaration, a president who sends US military forces into conflict must get authorisation from Congress if the hostilities last longer than 90 days.

Last week, Mr Obama informed Congress that administration lawyers deemed the Libya conflict did not require additional congressional approval, arguing US forces were merely playing a supporting role in the Nato campaign.

That role, the White House says, does not match the definition of "hostilities" as described in the War Powers resolution.

by Biodun Iginla, BBC News

Rebels in Libya have cheered US involvement

The US administration is examining the legality of continuing in the Nato-led Libya campaign beyond Friday.

The War Powers Resolution, passed after US withdrawal from the Vietnam War, rules that involvement in combat operations unauthorised by Congress must be terminated after 60 days.

That deadline is on Friday and deputy secretary of state James Steinberg has said the government is aware of it.

"President Obama has been mindful of the War Powers Resolution," he said.

In reference to the deadline, he said the administration was "actively reviewing" its role.

The president formally informed Congress of US involvement in Libya on 21 March.

White House lawyers are reportedly looking at ways US action in Libya can continue without contravening the resolution.

But Bruce Ackerman, a law professor at Yale University, says continuing without Congressional consent sets a dangerous precedent.

"A future president not as reasonable as President Obama is going to use this case to engage in something much more ambitious.

"From the point of view of long-term constitutional development, this is an important decision which will have precedental force in a very different context."

Congress passed the War Powers Resolution at the end of the Vietnam War, overriding President Nixon's veto.

It built on efforts by the founding fathers to repudiate the model of executive war-making, said Professor Ackerman.