Italy's Prime Minister has called on European leaders to hold an emergency meeting - after another migrant ship sank in the Mediterranean.

Up to 650 people are feared dead after their boat capsized between Libya and the Italian island of Lampedusa.

28 have been rescued and more than 20 bodies have been recovered from the Mediterranean Sea.

It is less than a week since a similar tragedy in which 400 other migrants drowned.

Foreign affairs ministers from across Europe are travelling to Luxembourg tonight, ahead of a scheduled meeting which will take place tomorrow.

The loss of approximately one thousand lives in the Mediterranean over the last week is set to top the agenda.

Colm O'Gorman of Amnesty International Ireland says the EU needs to take urgent action:

William Spindler is from UN refugee agency UNHCR.

He says the conflict zones in the Middle East need to be tackled, as many migrants are desperately trying to flee their homelands:

A major search and rescue operation by air and sea is taking place after the vessel, with up to 700 on board, went down about 120 miles south of the Italian island of Lampedusa.

It is believed to have overturned when migrants moved to one side of the overcrowded 20-metre long boat in a desperate bid to get off and be rescued as a merchant ship approached.

At least 28 people were saved in the Mediterranean, while 24 were confirmed dead amid fears for hundreds of others.

The alarm was raised at about midnight and the Italian coastguard and navy are continuing to search through the night for survivors.

Italian Prime Minister Matteo Renzi said officials were "not in a position to confirm or verify" that 700 people were on board the boat, which was on its way to Malta.

And he called for an emergency summit of leaders from across Europe to discuss how to prevent further deaths of migrants in the Mediterranean.

"We are working to ensure this meeting can be held by the end of the week. It has to be a priority," he said.

The capsizing comes amid a large number of migrants trying to leave Libya for Italian shores.

So far, at least 900 have died attempting the journey this year as boats capsized. This includes around 400 who were presumed drowned in a shipwreck last week.

The latest disaster could be the worst seen during the decades-long migrant crisis in the southern Mediterranean.

Carlotta Sami, from the United Nations High Commissioner for Refugees, said: "It seems we are looking at the worst massacre ever seen in the Mediterranean."

EU meeting

EU foreign policy chief Federica Mogherini said foreign ministers would discuss the issue at a scheduled meeting in Luxembourg on Monday.

British Foreign Secretary Philip Hammond, who will be at Monday's meeting, said: "We must target the traffickers who are responsible for so many people dying at sea and prevent their innocent victims from being tricked or forced into making these perilous journeys."

French President Francois Hollande said the EU must do more, telling Canal+ television that rescue and disaster prevention efforts needed "more boats, more overflights and a much more intense battle against people trafficking".

"Those who put people on these boats are smugglers," he said.

"They are even terrorists, because they know perfectly well that these boats are unsafe and that they will destroy the boats in the middle of the sea and put hundreds of people at risk to their lives."

Pope Francis also made a new appeal to EU leaders to act to stop the loss of life off Italy's southern coast.

International aid groups and Italian authorities have criticised Europe's so-called "Triton" border protection operation as inadequate to tackle the scale of the problem.

It has a much smaller budget and narrow remit that the more comprehensive Italian search-and-rescue mission which it replaced.

The "Mare Nostrum" or "Our Sea" operation was cancelled last year due to the cost.

Italy scaled back the mission after it was unable to persuade European partners to help meet its operating costs of nine million euros per month.

There were divisions over the mission as some politicians said it encouraged migrants to depart by raising their hopes of being rescued.

Originally posted at 9.34am