The operator of the Channel Tunnel says the number of migrants trying to enter Britain has dropped as new fencing and other security measures have begun to take hold.

Eurotunnel said Sunday the number of migrant incursions had dropped to about 150 a night — down from as many as 2,000 at the end of July.

British Prime Minister David Cameron has described the flow of migrants trying to enter Britain as a "swarm."

Cameron says Britain is one of the "most generous countries" in Europe in granting asylum to refugees. Still it has faced criticism for failing to take in any of the ever-rising tens of thousands of migrants who reach Europe by crossing the Mediterranean into Greece and Italy.