At least 732 migrants have died in the Mediterranean so far this year as they tried to flee poverty and violence, the International Organization for Migration (IOM) said Friday in Geneva.
In addition, at least 352 migrants have gone missing, according to the aid and advocacy organization.
Since January, more than 177,000 people have crossed the Mediterranean Sea to Southern Europe, three times as many as during the first four months of 2015.
Some 153,000 have landed in Greece, but arrivals have dropped sharply since the EU-Turkey migration deal came into effect in early April.
Only 174 people arrived on Greek islands in the past three days.
In contrast, Italy recorded 5,664 arrivals in the same period.
Italian and international vessels rescued 4,100 migrants earlier this week in the narrow Strait of Sicily. Most of them were travelling in rubber dinghies and wooden boats.
Most of the people who have ventured across the sea from Libya to southern Italy this year came from African countries such as Nigeria, Gambia or Senegal.
The majority of those who have travelled from Turkey to Greece are Syrians, Afghans or Iraqis.