David Cameron has said he is ready to commit British resources to a strengthened search and rescue operation in the Mediterranean as EU leaders prepared to meet to discuss the escalating migrant crisis.

The Prime Minister - who is breaking off from the election campaign to attend an emergency summit in Brussels - said he would be pressing for a "comprehensive approach" to the problem.

With experts warning the death toll could reach the tens of thousands as growing numbers of desperate migrants take to the waters in overcrowded and unseaworthy boats, Mr Cameron said authorities need to go after the people traffickers as well as addressing the instability causing them to flee.

"We now need to make a change and make sure there is more and search and rescue," he said during an interview with a studio audience on BBC Radio 1's Newsbeat.

"I will be arguing 'Let's have a comprehensive approach.' Yes, we need search and rescue. We can play a role with that. Britain's a wealthy country with strong assets. We can bring some of those to bear.

"But let's also go after effectively the modern slave traders. Let's also try and stabilise these countries - not just Libya but also Nigeria, Somalia, Eritrea, Ethiopia. It's these unstable countries that people are coming from that's part of the problem."

The summit was called after around 800 migrants were feared to have drowned when their boat capsized at the weekend off the coast of Libya in what the UN High Commissioner for Refugees said was the "deadliest incident" it had ever recorded in the Mediterranean.

The Ministry of Defence said that it was "looking at options" following reports that one of the Royal Navy's largest vessels - the assault ship HMS Bulwark - could be despatched to take part in the operation.

It is understood, however, that Mr Cameron will want to see what other EU leaders are prepared to offer at the talks before making a final decision on Britain's contribution.

His call for a comprehensive approach to the issue echoed Italian prime minister Matteo Renzi whose country has rescued hundreds of migrants after their ships ran into trouble.

Speaking in the Italian parliament today, he said that Italy's "noble, generous reaction alone isn't enough.

"We are asking Europe to be Europe, not just when it's time to devise a budget," he said.

Italian defence minister Roberta Pinotti suggested refugee camps should be set up in countries bordering Libya and said the human traffickers needed to be targeted with military intervention.

"We know where the smugglers keep their boats, where they gather. The plans for military intervention are there," she said.

"We think it's the moment in which Europe decides, forcefully, to have an international police operation, which will undo this band of criminals."

Earlier London mayor Boris Johnson suggested that British special forces could be sent to Libya, where many of the migrant boats sail from, in order to deal with the people traffickers.

"I think you need to choke off the problem at source - you need to stop these people being put into boats," he said on a LBC radio phone-in.

Maurice Wren, chief executive of the British Refugee Council, said it was essential that the summit addressed the wider issues causing people to flee - most from the Middle East or sub-Saharan Africa.

"If all of the focus is going to be on how we stop the boats, we are effectively ignoring the reasons why people are forced to board them in the first place," he told BBC Radio 4's The World at One.

"We are going to be sending what I think is an unacceptable message - that we don't mind if people are killed, we just don't want it to happen on our doorstep. Totally unacceptable.

"Europe has got a big decision to make tomorrow. It needs to put the principle of saving lives at the front and centre of its policy."

Mr Cameron strongly defended his decision to order RAF warplanes to bomb Libya in 2011 - despite claims that the chaos which followed the overthrow of Colonel Gaddafi was a major factor in the instability causing people to flee.

"We stopped a genocide," he said. "I could see what was happening, I could see people were going to be slaughtered in their hundreds, possibly in their thousands.

"I had a choice - act or stand to one side. We acted and it was the right thing to do."