The UN refugee agency says over 700 refugees may have drowned in three Mediterranean Sea shipwrecks south of Italy in the last few days.
Carlotta Sami, a spokeswoman for UNHCR, told The Associated Press news agency by phone on Sunday that an estimated 100 people were missing from a smugglers' boat that capsized on Wednesday.
She said about 550 others were missing from a boat that capsized on Thursday morning.
Refugees said that boat, which was carrying about 670 people, did not have an engine and was being towed by another smuggling boat before it capsized.
About 25 people from it survived, 79 others were rescued by patrol boats and 15 dead bodies were recovered.
Sami said 45 more bodies were recovered from a shipwreck on Friday and many more were reported missing.
In a separate development 19 refugees were rescued from a boat in English Channel, the AFP news agency reported, citing coastguard officials.