Hundreds are feared dead after a fishing boat carrying 600 migrants capsized in the Mediterranean just north of Libya.
The vessel crowded with migrants overturned as rescuers approached.
The Irish navy, whose rescue boat Le Niamh was the first on the scene, said it expected “significant loss of life” and aid organisation Medecins Sans Frontieres (MSF) confirmed “many deaths”.
Rescue efforts continued last night with the Italian coastguard and Irish navy confirming at least 367 people including 13 children were saved while 25 bodies were recovered in the latest human smuggling tragedy.
MSF said its Dignity I vessel was at the scene.
“The team on the #Dignity1 can confirm that there have tragically been many deaths but does not have figures at this stage,” it said in a tweet.
Coastguard Commander Filippo Marini said the rescue operation involved seven ships and that survivors indicated that between 400 and 600 people were aboard the smugglers’ boat.
A spokesman for the United Nations Commission for Refugees Federico Fossi said that as many as 100 people may have been in the hull when the boat capsized. The exact number of those aboard might never be known, but authorities hoped to have a better idea after survivors were interviewed.
Irish naval vessel Le Niamh was one of the ships tasked by the coastguard to speed to the rescue shortly before noon.
Cmdr Marini said that “at the sight of it, the migrants shifted” to one side and their boat capsized.
Speaking last night Simon Coveney, Ireland’s defence minister, said the death toll was significant and likely to rise.
“As the operation is currently ongoing, with all personnel fully engaged in the rescue, it is difficult to ascertain full details on the scale of the incident,” he said.
“However I understand that the fishing vessel capsized and that the loss of life is likely to be significant. The crew of the Niamh are working flat out with their counterparts to rescue as many as possible.”
He added: “Our thoughts and prayers are with all those who have lost their lives and the survivors and the rescuers.”
Last night rescuers worked with the hope of finding more survivors, as dusk approached. The vessel was reported to be 110km (about 75 miles) northwest of Tripoli, Libya’s capital.
It had set out from Zuwarah, close to the Tunisian border.
More than 2,000 people trying to make the crossing from Libya to Europe have died this year, according to the International Organisation for Migration.
Earlier this week, European Commission chief Jean-Claude said EU governments had a duty to help migrants trying to reach Europe and not give in to “populist” demands to refuse them entry. He was disappointed, he said, that EU ministers had not reached agreement last month on how to distribute some 40,000 mostly Syrian and Eritrean migrants from Italy and Greece.
In April, a crammed fishing boat sank, taking down with it perhaps as many as 800 migrants trapped inside the hold. Only 28 people, including two alleged smugglers, survived.
The International Office for Migration (IOM) has warned that the number of migrants attempting to cross the sea is much higher than in the same period last year.
In a statement IOM director general William Lacy Swing said: “It is unacceptable that in the 21st century people fleeing from conflict, persecutions, misery and land degradation must endure such terrible experiences and then die on Europe’s doorstep.”