As many as 700 migrants were feared drowned Sunday after their packed boat capsized off Libya in what was described as the deadliest such disaster to date in the Mediterranean.

As many as 700 migrants were feared drowned Sunday after their packed boat capsized off Libya in what was described as the deadliest such disaster to date in the Mediterranean.

The UN refugee agency (UNHCR) and Italy's coastguard said only 28 people had survived the wreck. Their testimonies suggested there had been about 700 people on board the 20-metre (70-foot) fishing boat, officials said.

"It seems we are looking at the worst massacre ever seen in the Mediterranean," UNHCR spokeswoman Carlotta Sami said.

The European Union announced an emergency meeting of foreign and interior ministers to discuss what Amnesty International blasted as an avoidable "man-made tragedy".

Coastal authorities in Italy and Malta picked up a distress signal from the stricken vessel around midnight (2200 GMT) on Saturday, when it was about 70 miles (126 km) off the Libyan coast and 110 miles (177 km) south of the Italian island of Lampedusa.

The Italian coastguard instructed a nearby merchant ship to go to the scene and it was when the Portuguese-registered King Jacob arrived at the scene that the fishing boat capsized, most likely as a result of the terrified passengers stampeding to one side in their desperation to get off, the UNHCR's Sami said.

A total of 17 boats scoured the area for survivors on Sunday but only 24 bodies had been recovered so far, the coastguard said.