According to the UN refugee agency, the United Nation Humanitarian Commission for Refugees (UNHCR), up to 700 migrants are feared drowned in a series of shipwrecks off the coast of Libya in the last few days.
The boats the migrants were travelling on sank south of Italy on Wednesday, Thursday and Friday as they tried to reach Europe in unworthy sea vessels, BBC reports.
Spring weather has led to a surge of people attempting the perilous crossing from Africa to Europe.
The route has become a key migration route since a deal curbed numbers sailing to Greece.
Spokeswoman for UNHCR, Carlotta Sami said almost 100 migrants are missing from a smugglers’ boat which capsized on Wednesday.
She noted that about 550 other migrants are missing from a boat which overturned on Thursday morning after leaving the Libyan port of Sabratha on Wednesday.
Survivors said the boat had no engine and was being towed by a second smuggling vessels.
According to Sami, in a third shipwreck on Friday, 135 people were rescued, 45 bodies pulled from the water and an unspecified number of others are missing.
However, The MSF sea group suggested the death toll from the last week could be as high as 900.
MSF Sea (@MSF_Sea) May 29, 2016
The Italian authorities have said the rescue of more than 600 migrants off Libya on Saturday by a flotilla of EU ships took the weekly total to at least 13,000.
The rescues were the latest by a multinational patrol of ships operating in the Mediterranean.
Sami said one of the most worrying things is that all the ships left together in just the last few days and has put rescuers under severe pressure.