More than 5,000 Palestinian refugees have fled a camp in the Syrian town of Latakia, under fire from Syrian troops, a UN agency said on Monday, calling for immediate access to the site.

"Thousands of the refugees have fled the camp. There are 10,000 refugees there and more than half of them have fled," said Chris Gunness, spokesman for the United Nations Relief and Works Agency, which helps Palestinian refugees.

"Between five and 10,000 people have fled," he said. "We need to get in there and find out what the hell is going on."