Around 60 migrants are missing in waters off Libya, the International Organisation for Migration said after interviewing survivors who were picked up from their stricken craft.
An Italian corvette, the Fenice, picked up dozens of migrants aboard a sinking rubber dinghy on Tuesday after the vessel was spotted by a naval helicopter.
Fifty-four were brought to the Italian island of Lampedusa, but according to testimony from survivors, the craft had set off with between 117 and 120 people on board, all of them from sub-Saharan Africa, the IOM said.
Over 30 of the passengers were women but there were no children, the agency said.
The UN High Commissioner for Refugees (UNHCR) last week said around a quarter of a million migrants had crossed to Europe by sea this year, of which 98,000 had arrived in Italy and 124,000 in Greece.
More than 2,100 had died in their bid to cross, it said.
By Pita Ochai
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