Libyan coast guards have rescued 27 illegal African migrants and dozens others are still missing after their boat sank off the coast of the northwestern Zliten city.

Libyan coast guards have rescued 27 illegal African migrants and dozens others are still missing after their boat sank off the coast of the northwestern Zliten city, a coast guard official told media outlets on Friday.

The official said that 72 migrants had been aboard the boat which sank Thursday night.

The coast guards recovered nine bodies while remaining migrants are still missing at sea and their nationalities could not be identified, the official said.

He said that the boat might have sailed off two days ago from a coastal suburb in Zliten, which lies some 150km east of capital Tripoli.

Illegal African migrants wishing to flee poverty and unemployment in their own countries routinely seek Libya's northern Mediterranean coast as a traditional gateway to Europe, especially Italy.

The ongoing conflict between Libya's political factions has loosened security at the borders, further weakening local authorities' capabilities in combating the phenomenon.

Over 3,000 illegal migrants entered Libya between March and August of last year, according to a recent UN report.

Libya has been dogged by political instability since the 2011 ouster and death of long-ruling strongman Muammar Gaddafi.

Ever since, rival militias have frequently locked horns, bringing violence to much of the country.