About 50 people have been found dead in the hold of a boat carrying migrants intercepted off the coast of Libya, the Italian coastguard says.
Italian media reports say the deaths were probably caused by asphyxiation.
About 430 people were rescued alive from the boat by a Swedish coastguard ship, the Poseidon, working with the EU's Frontex border agency.
Thousands of migrants have died and many thousands more have been rescued after setting sail from Libya recently.
Wednesday's rescue operation was one of 10 such missions currently taking place in the waters off Libya, the Italian coastguard said.