More than 40 migrants have died in an overcrowded boat in the Mediterranean, the Italian navy has said.
Many others were saved as the boat was intercepted off Libya. The navy said the rescue was continuing.
The deaths were caused by suffocation as the migrants were held in a confined space below deck, reports say.
European officials say the plight of migrants, 250,000 of whom have crossed by boat to the continent this year, is “beyond urgent”.
The Italian navy said it had co-ordinated the rescue of 1,700 people on Tuesday alone.
It tweeted (in Italian) that the ship Cigala Fulgosi was leading the latest rescue mission on Saturday and that many people had been saved.
The Italian news agency Ansa said the boat was in distress about 21 nautical miles (39km) off the coast of Libya and carrying about 400 migrants.
Interior Minister Angelino Alfano said about 320 people had been rescued but “they are still counting the victims”.
Navy spokesman Costantino Fantasia said the dead were “presumably in the hold”, but was unable to confirm this as the mission was still going on.
The navy rescued about 50 migrants from a rubber dinghy on Wednesday, but as many others were never found.
Another 200 are feared dead after their boat capsized off Libya on 5 April. Hundreds were rescued from that boat by the Irish navy.
So far this year. the United Nations says that more than 2,000 migrants have died trying to make the trip by sea to Europe.
The BBC’s James Reynolds in Rome says it has become the world’s most dangerous migrant journey.