A migration organization says that about 340 migrants have died or gone missing in four Mediterranean Sea shipwrecks over the past two-and-a-half days.

Flavio Di Giacomo, Italy spokesman for the International Organization for Migration, says that brings to over 4,500 the number of migrants who have died or disappeared so far this year making the risky sea voyage, the deadliest year on record.

Di Giacomo said Thursday that the recent toll includes a rescue overnight by Doctors without Borders of 27 migrants, who reported that more than 130 people had been on board their rubber dinghy when it sank. Seven bodies were recovered.

Di Giacomo said the toll is increasing this year as smugglers are forcing departures despite rough winter seas.