Thai officials say clashes have broken out in 12 locations along the disputed border, and acting Prime Minister Phumtham Wechayacha has said the conflict could "devolve into war."
At least 15 people have been killed in Thailand since Thursday, all but one of them civilians.
Cambodia has not released a death toll in the country, but a provincial government official said at least one civilian had been killed.
More than 100,000 civilians have been forced to flee their homes in Thailand from several border provinces, while 1,500 families in Cambodia's Oddar Meanchey province have been evacuated.
Phnom Penh has accused Thailand of using cluster munitions on Cambodian territory.
The UN Security Council is expected to meet later today on the conflict.
