Hundreds were feared dead after a boat packed with refugees sank off the Libyan coastal city of Zuwarah on Thursday.
A Zuwarah security official said, on condition of anonymity, that there had been 400 people on board and some appeared to have been trapped in the hold when it capsized.
By late Thursday evening, the Libyan coastguard had rescued about 201 people, of which 147 were brought to a detention facility for "illegal migrants" in Sabratha, west of the capital Tripoli, according to the security official quoted by Reuters.
Another local official and a journalist based in Zuwarah confirmed the sinking but had no information on casualties.
The refugees on board had been from sub-Saharan Africa, Pakistan, Syria, Morocco and Bangladesh, the security official said.
The Italian coastguard, which has been coordinating rescue operations by the European Union off the Libyan coast, could not immediately confirm a sinking.
Zuwarah, near the Tunisian border, is a major launching area for smugglers shipping refugees to the Italy, and the Mediterreanean Sea crossing is one of the deadliest routes for refugees.
Despite rescure efforts in Thursday's incident, Tripoli feels that Libya, already grappling with violent domestic conflict, should not have to expend resources dealing deal with en route to Europe, Anas El Gomati, who founded Tripoli-based think tank The Sadeq Institute, told Al Jazeera.
"Libya's security approach — and security apparatus — is now completely disorganized and in chaos," Gomati said.
"You have hundreds of different groups that are operating on the ground now, some of them taking advantage of a very, very chaotic situation, one of civil war," he said.
More than 2,300 people have died this year in attempts to reach Europe by boat, compared with 3,279 during the whole of last year, according to the International Organization for Migration.
As many as 50 refugees were found dead in a parked truck in Austria near the Hungarian border on Thursday, and German Chancellor Angela Merkel said the discovery had shaken European leaders discussing the migrant crisis at a Balkans summit.
Al Jazeera and Reuters