Libyan coastguards said they intercepted seven vessels on Sunday carrying around 850 African migrants trying to reach Europe illegally by sea.

"The coastguard in the west was patrolling the area off the Zawiya refinery (45 kilometres, 28 miles west of Tripoli) and ... they intercepted seven large inflatables," Libyan navy spokesman Colonel Ayoub Qassem told AFP.

He said the migrants "from several African countries" included 79 women -- 11 of them pregnant -- and 11 children.

"The migrants were handed over to the authorities for transfer to shelters," he said.

The chaos in the North African country since Moamer Kadhafi's fall in 2011 has been exploited by people traffickers, with thousands of migrants trying to reach Europe from Libya just 300 kilometres from Italy.

The onset of better weather conditions has raised fears of huge numbers of people attempting the still perilous sea crossing.

At the end of March, French Defence Minister Jean-Yves Le Drian estimated that around 800,000 migrants were waiting to head for Europe from Libya.

On May 13, a British parliamentary report said the EU's naval mission to combat people trafficking off the Libyan coast was "failing" and had only succeeded in forcing smugglers to change tactics.

Operation Sophia "does not in any meaningful way deter the flow of migrants, disrupt the smugglers' networks or impede the business of people smuggling on the central Mediterranean route", it said.

Committee chairman Lord Tugendhat said the mission to patrol an area six times larger than Italy "was always going to present an enormous challenge".

"The smuggling networks operate from Libya, and they extend through Africa. Without support from a stable Libyan government, the operation is unable to gather the intelligence it needs or tackle the smugglers onshore," he said.