Hundreds of people are feared to have drowned after a boat carrying up to 700 migrants capsized in the Mediterranean Sea, the Italian coastguard says.
The vessel, thought to be just 20m (70ft) long, capsized at midnight local time in Libyan waters south of the Italian island of Lampedusa.
So far only 28 people have been rescued and 24 bodies retrieved.
Italy’s PM said it was a European tragedy and called for an extraordinary EU summit on the migrants issue.
Matteo Renzi said he could not verify the number of deaths, but that it would be a “dramatic amount”.
The UN refugee agency, the UNHCR, said the latest sinking could amount to the largest loss of life during a migrant crossing to Europe. At least another 900 migrants have died crossing the Mediterranean this year.
Italian naval and coastguard ships, the Maltese Navy and cargo vessels, along with three helicopters, are involved in the rescue operation, 130 miles (210km) off the coast of Lampedusa and 17 miles from the Libyan coast.
The Italian coast guard’s spokesman told the BBC the operation was still focused on search and rescue, “but in time it will be a search [for bodies] only”.