More than 700 migrants may have drowned in the Mediterranean trying to reach Europe in the last few days, according to the UN.
The UN's refugee agency says the migrants died as their unseaworthy smuggling boats sank south of Italy.
Carlotta Sami, spokeswoman for UNHCR, said that an estimated 100 people are missing from a smugglers' boat which capsized on Wednesday.
The Italian navy took pictures of it capsizing as it rushed to rescue all those thrown into the sea.
She said about 550 others are missing from a smuggling boat that sank on Thursday morning after leaving the western Libyan port of Sabratha a day earlier.
Refugees have told her that boat, which was carrying about 670 people, didn't have an engine and was being towed by another packed smuggling boat before it capsized.
In a third shipwreck on Friday, Sami said 135 people were rescued, 45 bodies were recovered and an unknown number of people are missing.
Survivors are being taken to the Italian ports of Taranto and Pozzallo.
Italy's southern islands are the main destinations for countless numbers of smuggling boats launched from the shores of lawless Libya each week.
Rescues
Meanwhile, 19 people have been rescued in the English Channel after their inflatable boat took on water.
A call for help was made off the coast of Dymchurch in Kent at 11.40pm last night. The inflatable boat was found at 2am.
Italian authorities said yesterday that 13,000 people have been saved from the Mediterranean Sea in the past week.
Over 650 people were rescued yesterday alone - 347 of them by the Irish naval vessel the LÉ Róisín.
