A boat carrying up to 250 African migrants seeking asylum in Europe sank off the Libyan coast on Sunday.

Only 26 passengers have been rescued so far, navy spokesman Ayub Qassem told Reuters yesterday.

"There are so many dead bodies floating in the sea," he said.

The boat capsized near Tajoura, 15kms east of Tripoli, the Libyan capital. Most of those on board were Africans; Libya has become a major port for migrants trying to leave for Europe.

Those who do arrive in safety end up in Italy, Greece, Spain and Malta. An Italian government official said in August that almost 100,000 migrants had arrived on Italian shores so far this year.

Numbers leaving Libya have increased amid growing unrest in Tripoli and Benghazi.

The United Nations said earlier this month that 150,000 people had been forced to flee the violence between rival militant groups, and a further 100,000 people had been internally displaced.

Human traffickers are thought to be taking advantage of the political turmoil within the country.

More than 100 people died in a similar incident in August, when a boat sank off the Libyan coast. Many on board that boat were Eritreans and Somalis also seeking asylum in Europe. At least 50 passengers were never recovered.

About 800 migrants died in boats crossing the Mediterranean between January and July, the United Nations Commission for Human Rights said. Numbers trying to make the crossing are about 60 per cent higher than the whole of last year.

Italian Prime Minister Matteo Renzi said in June that the EU must take responsibility for rescuing migrants attempting to cross the Mediterranean.