Dozens of migrants have drowned in the Mediterranean after a boat sank south of Sicily, the Save the Children aid group says.
It says survivors reported that many people fell into the sea as a rescue vessel was approaching.
The survivors arrived in the city of Catania on Tuesday.
At least 1,750 people have died this year trying to cross the Mediterranean, a 20-fold increase on the same period in 2014.
In the latest incident, survivors were cited as saying that about 40 people had drowned.
Giovanna di Benedetto, Save the Children's representative in Catania, said the sinking is thought to have happened on Sunday, but the exact toll was not known.
The Italian coastguard has not confirmed the death toll.
Over the weekend more than 5,800 migrants were rescued and 10 bodies recovered off the Libyan coast, according to the Italian coastguard.
Italian and French ships picked up survivors from wooden and rubber boats in 17 separate operations.
The latest deaths come as naval chiefs from 26 European countries are due to discuss the migrant crisis at talks in Naples, southern Italy.