On Saturday, Cambodian authorities reported 12 new deaths, bringing its toll to 13, while Thai officials said a soldier was killed, raising the number of deaths to 20 – mostly civilians.
New flashpoints emerged on Saturday more than 100 km (60 miles) from other conflict points along the long-contested border.
There were clashes in the early morning in the neighbouring Thai coastal province of Trat and Cambodia’s Pursat Province, both sides said.
International pressure is mounting on both sides to declare a ceasefire.
At an emergency meeting in New York late on Friday, the UN Security Council unanimously called on both sides to show restraint and resolve the dispute peacefully, a council diplomat speaking on condition of anonymity said.
Malaysia, which chairs the 10-nation Association of Southeast Asian Nations (ASEAN), which includes both parties, called for an end to hostilities and offered to mediate.
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Cambodia’s defence ministry said Thailand had launched “a deliberate, unprovoked, and unlawful military attack” but Thailand’s acting prime minister, Phumtham Wechayachai, said Bangkok had exercised the “utmost restraint and patience in the face of [Phnom Penh’s] provocations and aggression”.
Cambodia’s Information Minister Neth Pheaktra said on Saturday the clashes had forced 10,865 Cambodian families – 37,635 people – in three border provinces to evacuate, while Thai officials said more than 131,000 people had fled their border villages.
Villages around Cambodia’s Oddar Meanchey province were largely deserted, as people loaded their belongings on homemade tractors or sheltered in makeshift underground bunkers, covering them with wood, tarpaulin and zinc sheets to shield themselves from shelling.
Several hundred residents went to a remote Buddhist temple where plastic tents were set up under the trees.
There have been frequent flare-ups along the 500 mile (800 km) frontier the two nations share, and 20 people died in the last serious clashes in 2011.
Tensions rose again in May when a Cambodian soldier was killed in a skirmish and escalated further when a land mine wounded five Thai soldiers on Wednesday.
The situation grew into a full-blown diplomatic crisis as Bangkok closed the border and expelled the Cambodian ambassador.
Both sides reinforced their troops on the border and clashes broke out the following day.
On Friday, the Thai military reported clashes in multiple areas along the border, including near the ancient Ta Muen Thom temple claimed by both sides.
