A human rights group says nearly 2,000 migrants are known to have died so far this year crossing the Mediterranean, outpacing last year's death toll.

The International Organization for Migration said in a release on Tuesday that about 1,930 perished trying to reach Italy in unseaworthy boats mostly departing from Libya. Another 60 died trying to reach Greece.

IOM chief William Lacy Swing called the deaths of migrants fleeing conflict and other hardship "unacceptable."

The latest deaths were recorded last week when 19 people perished, most from heat exhaustion and thirst after drinking water was used to cool a boat's engine. Officials note that not all migrant deaths are known.

In the same period last year, the IOM says 1,607 migrants had perished. The year-end death toll was 3,279.