At least 40 people have died and 51 have been rescued after a boat carrying migrants sank off Libya's coast, the Libyan Interior Ministry has said.

Al Jazeera's Omar Al Saleh, reporting from Tripoli, said there were conflicting reports on the date of the incident and the number of casualties.

"The Libyan Navy says at least 74 migrants are still missing, after 20 bodies were recovered on Sunday following Friday's shipwreck."

But the AFP news agency quoted a naval official as saying the boat carrying 130 migrants sank on Tuesday.

The boat capsized off Garabulli, 50km east of the Libyan capital Tripoli and was reported to have been en-route to Europe.

On Saturday, Interior Minister Saleh Maziq threatened to help illegal migrants reach Europe if the European Union did not do more to help Libya deal with a flood of migrants using Libya as a transit point.

Libya's porous borders with its sub-Saharan neighbours and its proximity to Italy and Malta across the Mediterranean have made the North African country a common transit route for migrants trying to reach Europe.

Source: Al Jazeera and agencies