A spokesman for the United Nations Relief and Works agency (Unrwa) said that more than 5,000 of the 10,000 refugees were on the move.

He said at least four people had died, urging immediate access to the site. Some 30 people have reportedly died in Latakia in a three-day military attack. Syria says it is tackling gangs.

On Monday, there were also reports of a clampdown in the capital Damascus, with people being arrested randomly in the Jobar district.

Turkish Foreign Minister Ahmet Davutoglu warned Syria that military operations against protesters must stop "immediately and unconditionally".

Ankara, a former close ally of Damascus, has been increasingly frustrated with its crackdown of the unrest.

The Palestinian authorities urged the Syrian government to safeguard the lives of Palestinian refugees.

In Washington, White House spokesman John Carney said that Syrian President Bashar al-Assad must "cease the systematic violence, mass arrests and the outright murder of his own people."

More than 1,700 people have reportedly died and more than 30,000 have been detained in the five-month uprising against President Assad's rule.