Thai and Cambodian soldiers are continuing to clash along the border between their countries in a major escalation that has so far left at least 14 people dead, mostly Thai civilians.

The two sides fired small arms, artillery and rockets, and Thailand also launched air strikes in the bloodiest military battles in more than a decade between the two South-East Asian neighbours.

The conflict presents “a big headache” for South-East Asia, a leading expert says, with questions remaining over how the two countries and the region will respond.

Land mine triggers escalation

Fighting took place in at least six areas on Thursday, according to Thai Defence Ministry spokesperson Surasant Kongsiri, a day after a land mine explosion along the border wounded five Thai soldiers.

The incident led Bangkok to withdraw its ambassador from Cambodia and expel Cambodia’s envoy to Thailand.

Cambodia fired rockets and artillery shells into Thailand and the Thai military scrambled F-16 jets to carry out air strikes.

In Bangkok, the Public Health Ministry said a Thai soldier and 13 civilians, including children, were killed while 14 soldiers and 32 other civilians were injured.

Most of the causalities were caused by a rocket strike near a petrol station in Sisaket province.

Public Health Minister Somsak Thepsuthin condemned what he said were the attacks on civilians and a hospital as violations of international humanitarian law and the Geneva Conventions.

“We urge the Cambodian government to immediately halt these war criminal actions, and return to respecting the principles of peaceful coexistence,” he said.

On Friday, Cambodia’s chief official in Oddar Meanchey province, General Khov Ly, said clashes resumed early in the morning near the ancient Ta Muen Thom temple.

Associated Press reporters near the border could hear sounds of artillery from early morning hours.

The official also said that at least four civilians were wounded in Thursday’s fighting there and that more than 4,000 people had been displaced from their villages along the border to evacuation centres.

It was the first account of any casualties from the Cambodian side.

The escalation represents a rare instance of military conflict between member countries of the Association of South-East Asian Nations (ASEAN), though Thailand has tangled with Cambodia before over the border and has had sporadic skirmishes with western neighbour Myanmar.

UN Secretary-General Antonio Guterres urged both sides “to exercise maximum restraint and address any issues through dialogue”, according to UN deputy spokesperson Farhan Haq.

Thailand and Cambodia have blamed each other for the clashes, alleging that civilians were being targeted.

The fighting is the latest chapter in a long-running spat over an area known as the Emerald Triangle, where the borders of both countries and Laos meet.

The decades-old squabble flared into bloody clashes more than 15 years ago and again in May, when a Cambodian soldier was killed in a firefight.

It remains unclear why Cambodia targeted a petrol station in Thailand.

Praphas Intaracheun, a 53-year-old gardener from Sisaket, told AFP that he was refuelling at another petrol station about 300 metres from the one that was hit on Thursday.

“I heard a loud noise three or four times, and when I looked over, there was a gigantic cloud of smoke,”

he said.

A 30-bed hospital in the town of Phanom Dong Rak in Surin province, just 15 kilometres from the border, was hit by shells which shattered windows and collapsed part of a roof.

The facility was partially evacuated on Wednesday night as a precaution.

The Phanom Dong Rak hospital in Thailand was damaged by Cambodian artillery. (AP Photo: Sunny Chittawil)

Locals flee border zones

Fighting was focused on six locations, the Thai army said, with ground troops and tanks battling Cambodian forces for control of territory.

Six Thai air force jets were deployed, hitting two “Cambodian military targets on the ground”, according to Thai military deputy spokesperson Ritcha Suksuwanon.

AFP journalists met Cambodians fleeing their villages near the Thai border to escape the fighting.

“We dare not to stay. They were fighting so bad that my house was shaking,” Say Vuthy said.

“We already dug a bunker but we dared not stay because we were scared that they will keep fighting at night.”

In Cambodia, several hundred villagers moved from their homes near the border to about 30 kilometres deeper inside Oddar Meanchey province.

Many made the journey with entire families and most of their possessions on home-made tractors, before settling down with hammocks and makeshift shelters.

From the encampment near the town of Samrong, a 45-year-old mother of four, Tep Savouen, said it all started about 8am.

“Suddenly I heard a loud noise,” she told the AP. 

“My son told me it might be thunder and I thought ‘Is it thunder or is it loud, more like a gun?′ At that time I was very scared.”

People rest at a shelter in Surin province in Thailand on Thursday. (Reuters: Pansira Kaewplung)

Director of the Asia-Pacific program at policy think tank Chatham House, Ben Bland, said that domestic politics and public opinion were key driving factors in the conflict.

“We know that a lot of temples that are on the border are really important, symbolically and culturally, for people in Cambodia,” Mr Bland said.

“We know Cambodia has been invaded in the past. It’s gone through decades of conflict. Thailand is also a proud country and has a very messy domestic politics right now. So, I think to a certain extent, this has been driven by politics and sustained by … some nationalist opinion in both countries.”

Thai Foreign Ministry spokesperson Nikorndej Balankura said the government was “prepared to intensify our self-defence measures if Cambodia persists in its armed aggression and violations upon Thailand’s sovereignty”.

In the Cambodian capital of Phnom Penh, Defence Ministry spokesperson Lieutenant General Maly Socheata said his country deployed armed force because “it has no choice but to defend its territory against Thai threats”.

The spokesperson insisted the Cambodian “attacks are focused on the military places, not on any other place”.

Cambodian Prime Minister Hun Manet wrote to the UN Security Council asking for an urgent meeting “to stop Thailand’s aggression”.

The council scheduled an emergency closed meeting at 3pm in New York on Friday.

Mr Bland said the violence was “really concerning” but both countries had shown the ability to de-escalate tensions in the past.

“There’s more of a risk that it becomes a protracted diplomatic and economic battle between the two, and I think that would potentially have knock-on effects economically,” Mr Bland said.

“It just creates another point of tension for South-East Asian nations when they’re already facing the impacts of the civil war in Myanmar, US-China tensions and Trump’s tariffs.

“It’s another big headache for the region, but it’s still early days.”

Locals in Surin province in Thailand were forced to take shelter during the attacks. (AP Photo: Sunny Chittawil)

Malaysia’s Prime Minister Anwar Ibrahim posted on X that he had spoken to both Cambodia’s Prime Minister Hun Manet and Thailand’s acting prime minister Phumtham Wechayachai.

Malaysia is the current chair of ASEAN.

“I appealed directly to both leaders for an immediate ceasefire to prevent further hostilities and to create space for peaceful dialogue and diplomatic resolution,” Mr Anwar posted.

“I welcome the positive signals and willingness shown by both Bangkok and Phnom Penh to consider this path forward.”

The United States, European Union, France and China, a close ally of Phnom Penh, all called for peace.

Army vehicles drive along a road in Buriram province, after Thailand scrambled an F-16 fighter jet. (Reuters: Athit Perawongmetha)

“We are deeply concerned over the current developments [and] hope both sides can properly resolve issues through dialogue and consultations,” Chinese Foreign Ministry spokesperson Guo Jiakun said.

Mr Bland said China ought to play a part in bringing about peace.

“It has extensive economic links with both countries … it clearly has huge interests in one neighbour and one close partner not being at loggerheads with each other,” he said.

“China’s approach to conflict is often mitigation rather than mediation or resolution. So I think they’ll be standing on the sidelines for now. But really if China does aspire to a bigger role in regional global security, which they often talk about rhetorically, this is the sort of case where you might expect or even hope that they would play some sort of bigger role, but we will have to see for now.”

The Australian government has urged travellers to reconsider the need to travel to border areas in both Cambodia and Thailand because of the conflict.

ABC/Wires