London (AFP) - Britain is to send several vessels to take part in a NATO mission to tackle people smugglers in the Aegean Sea, Prime Minister David Cameron announced Monday as European leaders met to discuss a migration crisis.

Cameron announced that the Royal Navy would send the amphibious landing ship RFA Mounts Bay, which would join two Border Force cutters and a chartered civilian vessel already in the sea between Greece and Turkey, a key crossing point for refugees and migrants heading to the European Union.

The navy ship carries a helicopter on board, and it is expected to shortly begin missions to spot smugglers ferrying people to Greece. The Turkish coastguard will be informed of sightings so they can intercept the boats.

"This migration crisis is the greatest challenge facing Europe today," Cameron said in a statement released before he headed to Brussels for a summit of EU leaders.

"We've got to break the business model of the criminal smugglers and stop the desperate flow of people crammed into makeshift vessels from embarking on a fruitless and perilous journey."

The British ships will join vessels from Canada, Germany, Greece and Turkey on the unprecedented mission, launched earlier this month to help the European Union cope with its worst migration crisis since World War II.

Cameron described the mission as "an opportunity to stop the smugglers and send out a clear message to migrants contemplating journeys to Europe that they will be turned back".

More than a million migrants fleeing war in Syria and upheaval across the Middle East, Asia and Africa landed in the European Union last year, the bulk of them making the perilous journey across the Aegean Sea from Turkey to Greece.