by Biodun Iginla and Natalie de Vallieres, BBC News

Volunteers and doctors work on the boat on which the bodies were found

Italian coastguards have found the bodies of 25 men on a boat crowded with refugees fleeing Libya.

The 15-metre boat landed on the southern Italian island of Lampedusa carrying 271 survivors, Agence France Presse (AFP) reported.

The bodies of 25 men were found in the boat's engine room. They appear to have died from asphyxiation, officials said.

Thousands of refugees from North Africa have arrived on the island in recent weeks.

The coastguard boarded the boat at around 01:20 on Monday (11:20 GMT on Sunday) and discovered the bodies.

Italian media reported that the people in the engine room had apparently tried to escape but had been trapped by the numbers on board and probably been choked by engine fumes.

The engine room was only accessible through a 50-centimetre (20-inch) wide trap door from the deck, an official said.

Italian investigators say some of the corpses had already begun decomposing when they were recovered by firemen and they believe the refugees died in international waters.

"Given the state in which the corpses were found, they could have been dead for at least 48 hours," doctor Pietro Bartolo told reporters. Survivors said they had been at sea for three days.

The corpses have been taken to the morgue for post-mortem examinations and police are questioning survivors.

Reuters news agency reported some survivors as saying another man's body had been dropped overboard after he died on the journey.

Lampedusa is now the biggest gateway to the European Union for refugees from North Africa. Some 250 refugees drowned when their boat capsized off the island in April.

BBC correspondent David Willey says the European Union's plan to deal with the large numbers of migrants has disappointed Italians, who feel they have been left to deal with the crisis on their own.