LONDON — Almost two shiploads of migrants, 245 in total, were feared dead in wrecks in the Mediterranean Sea, United Nations officials said on Tuesday. The death toll represents a major increase in an already grim tally this year.

More than 1,300 people are now estimated to have died so far this year while trying to cross the Mediterranean to Europe, most while trying to reach Italy from Libya or Tunisia, according to the International Organization for Migration. Last year, 5,098 people died that way.

The two recent shipwrecks occurred on Friday and Sunday, though details about the extent of the loss of life were not released until Tuesday.

On Friday night, a rubber dinghy sank after several hours at sea, with 132 people on board. Of those, 50 were rescued and taken on Sunday to Pozzallo, Sicily; an additional 82 were believed to have died.