Prime Minister David Cameron described the escalating deaths of migrants attempting to cross the Mediterranean as a "tragedy", as the government came under mounting criticism for its decision to cut funding for search and rescue operations in the area.

With more than 700 believed to have been killed after a vessel conatining migrants capsized off the coast of North Africa, Cameron said the EU needed to respond "urgently" to address the crisis and prevent the further loss of life.

"All three leaders agreed that the criminal networks behind human traffickers were primarily to blame for this tragedy, and that the highest priority had to be action to disrupt their activities," said a Downing Street spokesman.

Cameron warned on EU referendum
David Cameron has come under attack for the government\'s decision to scrap funding for search and rescue operations in the Mediterranean Reuters

"The Prime Minister stressed the need for a comprehensive approach to the crisis, which included action to stabilise migrants' home countries, and using all the tools at our disposal to go after the human traffickers."

However, the government's support for a decision in 2014 to cut joint EU funding for search and rescue missions to prevent migrants drowning in the Mediterranean Sea has been roundly attacked, with ministers refusing to review the decision in the wake of the deaths.

The Refugee Council said the mounting death toll exposed the disastrous consequences of the decision.

Dr Lisa Doyle, the Refugee Council head of advocacy, said: "Building the walls of fortress Europe has had disgracefully deadly results. It's time for a new approach, which prioritises saving lives and opening up alternative routes to safety. As we've seen, it's a matter of life and death."

The coalition government is criticised by the SNP and Labour

The SNP and Labour both joined in the criticism, and called for UK support for the search and rescue operations to be reinstated.

Labour leader Ed Miliband said: "For the second time in a matter of days we are seeing tragic scenes from the Mediterranean. These are unnecessary deaths of some of the poorest men, women and children in the world. European leaders must work together, we must act, to stop more of these drownings taking place."

Shadow Home Secretary Yvette Cooper added: "The British Government must immediately reverse its opposition to EU search and rescue operations in the Mediterranean."

Scotland's External Affairs Secretary Fiona Hyslop of the SNP said: "I have continually lobbied the current Tory/Lib Dem government to reverse their position to support planned search and rescue operations in the Mediterranean. We cannot allow the Mediterranean to be Europe's watery grave."

In October 2014, Foreign Office minister Baroness Anelay described the presence of rescue patrols as a "pull factor" encouraging migrants to risk the crossing.

In response, Mare Nostrum, a dedicated search and rescue operation had to close, as the Italian government did not have sufficient funds to operate it alone, and a scaled back operation involving only six ships was introduced, with a narrower border patrol remit.

UK Home Secretary Theresa may is currently in an emergency meeting with European ministers to discuss the crisis and co-ordinate a response.

It is believed nearly 2,000 migrants have been killed making the crossing across the Mediterranean this year. By April 2014, when the Mare Nostrum operation was in place, 100 had been killed.