Hundreds of migrants attempting the perilous journey across the Mediterranean are feared to have drowned after their overcrowded fishing boat capsized off Libya, Italy’s coastguard said on Wednesday.

The boat had run into difficulty 15 nautical miles off Libya and sent out a distress call, picked up by the coastguard in Catania in Sicily.

Two vessels – the Médecins Sans Frontières ship Dignity I and Irish patrol vessel Le Niamh – were immediately dispatched to the scene, but the boat capsized after the migrants all rushed to one side in anticipation of being rescued, the coastguard said.

An Irish naval official told the Associated Press that about 150 migrants were spotted in the water.

Nawal Soufi, an Arabic-speaking Italian based in Sicily who is often contacted by migrants in distress, told AFP she had taken a call earlier on Wednesday about a boat in trouble with 600 people on board.

“It is probably the same boat,” coastguard spokesman Filippo Marini said, raising fears that hundreds of people may have drowned.

Three other ships have been sent to the area to search for survivors.

More than 2,000 people have died trying to cross the Mediterranean to Europe this year, according to the International Organisation for Migration. The Guardian