At least 116 migrants are missing and another 132 were rescued by Libyan coast guards and local fishermen after a wooden boat capsized off Libya, Libyan Navy spokesman, Ayoub Qassem, on Thursday said.
Citing initial findings, he said there had been more than 200 migrants on board the boat, which capsized off the coast near Komas, a town east of the capital Tripoli.
He said one body had been recovered so far.
Earlier, the UN refugee agency UNHCR said that up to 150 people were feared dead while another 150 were rescued.
If confirmed, that death toll would be the highest for a shipwreck in the Mediterranean this year.
Libya is a hub for migrants, many of whom try to reach Europe in unseaworthy boats.
The ship left Libya from Komas, 120 km (75 miles) east of Tripoli.
The survivors were picked up by local fishermen and then returned to the coast by the Libyan coastguard, UNHCR spokesman, Charlie Yaxley, said.
The UNHCR and other UN agencies have repeatedly called for survivors not to be returned to Libya, a conflict zone where rescued migrants and refugees are routinely jailed in inhumane conditions and are vulnerable to being caught up in fighting.