International Organization for Migration spokesperson says the boat was believed to be carrying 110 people. Eight bodies were recovered in the rescue operations, which are hampered by poor conditions.
The Italian coast guard said on Saturday that around 100 people are feared drowned after a boat capsized 50-kilometres from the Libyan coast, on its way to Italy.
Rescue operations are under way for the missing people but poor conditions are hampering the search, said the coast guard. It said eight bodies were recovered so far.
The boat was believed to have carried 110 people, said Flavio di Giacomo, a spokesperson for the International Organization for Migration (IOM) said.
Authorities are still trying to work out the nationalities of the refugees.
Last year a record 181,000 boat migrants, mostly from Africa, reached Italy, according to government figures. The majority paid Libyan people traffickers to make the journey.
2016 was also the deadliest year on record for refugees in the Mediterranean, with almost 5,000 deaths, according to IOM.