Clashes erupted after the army entered the town at dawn. Sources said three people had died.

The government said it was trying to restore order after 120 security personnel were killed last week. Residents say they died after a mutiny and fighting between security forces.

The government operation sent hundreds more people fleeing towards the Turkish border, to join thousands who have already crossed.

The number of those who have crossed is probably higher than the official figure of 5,050 given on June 12 by the UN's refugee agency, the UNHCR.

Witnesses said there might be as many as 10,000 sheltering in the area. US officials say the crackdown has created a humanitarian crisis, and called for the International Committee of the Red Cross (ICRC) to be given access.

No-one is aware of the real magnitude of the problem and this is a big issue, because it does not allow us to know the size of the problem and then to act accordingly," said ICRC spokesman Hicham Hassan.