Aid agencies and the Irish Navy are reporting that a fishing vessel carrying about 600 migrants capsized in the Mediterranean and a distress call was issued, about 24 kilometers north of Libya.
The navy reports say hundreds of people were in the sea and a rescue effort was under way. The Associated Press cited Irish Naval Capt. Donal Gallagher as saying the Irish vessel was one of several ships requested by the Italian coast guard to speed to the rescue of the overturned boat.
Late Wednesday, aid agencies reported that some 400 migrants have been rescued and 25 bodies recovered.
"An Italian [military] helicopter has dropped additional life rafts'' into the sea, Capt. Gallagher told The Associated Press by phone.
Italy was helping to coordinate the rescue efforts and a vessel operated by Doctors Without Borders was on the scene.
Doctors Without Borders said it rescued 94 people, including 17 women and a 5-year-old boy.
Leonard Doyle, a spokesman for the International Organization for Migration, said the boat was overloaded.
The IOM says more than 2,000 migrants have died this year attempting to flee war and oppression from North Africa and the Middle East. Most aim for European shores.