The bodies of at least 11 African migrants have been found on the coast of Sicily, Italian authorities said.
Italy has strict new laws against illegal immigration
A number of teenagers were among the dead discovered on the beach at Gela and in the sea on Sunday.
Coastguards rescued more than 140 other immigrants from a nearby boat. Most of the people are thought to have come from Eritrea.
The migrants are believed to have made the crossing from Libya. Survivors said the boat ran aground close to shore.
They said they were told to jump into the sea when it happened on Saturday night a few hundred metres from the shore, the BBC's correspondent David Willey said from Rome.
The small trawler in which they had made the two-day crossing from Libya was seized by coastguards.
Police arrested six Egyptians and a Libyan who they believe organised the trip.
Survivors said they had paid more than $2,000 (£1,086) to make the trip from the Horn of Africa via Sudan and Egypt, and across the Libyan desert.
Most of the migrants are expected to be sent back to their own countries under tough new Italian immigration laws.