Fifty-seven migrants are known to have have drowned in the Mediterranean Sea after their boat capsized while trying to cross to Europe.

The Tunisian Ministry of Defence said the rubber boat left Libya's shores on Sunday with 90 people on board before it capsized.

There were 33 survivors - most of them believed to be Bangladeshi nationals - who reportedly survived by clinging to an oil rig.

They have now been taken by the Tunisian authorities to the port of Zarzis.

At least 1,200 migrants died last year attempting to cross the Mediterranean, and more than 500 people have already died since the start of this year.