Hundreds Feared Dead in Capsize

The coastguard said in a statement that the migrants' 66ft vessel was reported to be sinking as a Portuguese-registered merchant ship, the King Jacob, approached to attempt a rescue.

It picked up 28 passengers, but the boat then capsized, sending hundreds more into the water, The Press Association reported.

The coastguard's command and rescue coordination center in Rome said the boat might have overturned "because its occupants moved to the side closest to the cargo ship".

Italian news agency ANSA said the boat could have held 700 passengers, but the coastguard and other authorities said they had no immediate way to determine how many were aboard or how many might still be rescued.

Pope Francis was among those following the news. "There are fears there could be hundreds of dead," he told the faithful in St Peter's Square. He bowed his head in silent prayer as did many of the tens of thousands in the crowd.

Wreckage of the boat was spotted in the sea.

"There are large fuel stains, pieces of wood, life jackets," Italian border police General Antonino Iraso, whose force has boats deployed in the rescue effort, told Sky TG24 TV.

When asked whether the boat capsized because the migrants rushed to one side as the Portuguese vessel pulled alongside, Gen Iraso replied, "The dynamics aren't clear. But this is not the first time that has happened."

Italy is the top destination for illegal immigration to the European Union, and the numbers of migrants attempting the dangerous crossing by sea from Libya swells as the springtime weather improves, providing calmer seas and warmer water. But the smugglers' boats are invariably overcrowded and often too small for the open seas.

So far this year, more than 900 have died in failed crossings. Last week, 400 people were presumed drowned when another boat capsized.