Thailand and Cambodia have traded accusations of targeting civilians in artillery and rocket attacks as US President Donald Trump pledged to intervene to stop the fighting and salvage a ceasefire he brokered earlier this year.
Clashes raged at more than a dozen locations along their 817km border in some of the most intense fighting since a five-day battle in July, which Trump stopped with calls to both leaders to halt their worst conflict in recent history.
The Southeast Asian neighbours have blamed each other for the clashes that started on Monday.
Trump said he would try to stop the renewed hostilities, telling reporters that he expected to speak with the countries' leaders on Thursday.
"I think I can get them to stop fighting," he said.
Thailand's army has made clear it wants to cripple Cambodia's military capabilities and Prime Minister Anutin Charnvirakul said operations would not stop.
He declined to comment on Wednesday on what the military's endgame was.
Asked about Trump's remarks, he said the conflict was a matter between the two countries involved.
"Other national leaders may have good intentions in wanting peace," Anutin told reporters.
"It cannot be as simple as picking up the phone and calling. There must be proper appointment and agreed talking points. We still have time to prepare these issues if such discussions are to take place."
Cambodian government spokesperson Pen Bona said Phnom Penh's position was that it wanted only peace and had acted in self-defence. A top adviser to Cambodia's prime minister has signalled the country was ready to negotiate.
Thailand's army said fighting took place on 16 different fronts on Wednesday, including both ends of the border. It reported an onslaught of BM-21 rockets fired by Cambodian forces, some of which it said landed near a hospital in Surin province, forcing the evacuation of patients and staff.
The army said Cambodian drones were being used to drop bombs and BM-21 rockets, and tanks were used at other border areas, including near the contested 11th-century Preah Vihear temple, a flashpoint for previous diplomatic and military conflicts.
Cambodia's military said Thailand used artillery fire and armed drones and fired mortars into homes, while F-16 fighter jets had entered Cambodian airspace on multiple occasions, some dropping bombs near civilian areas.
"Cambodian forces have been fighting fiercely against the advancing enemy and have stood firm in their role of protecting Cambodia’s territorial integrity," the defence ministry said in a statement.
Last month, Thailand suspended de-escalation measures, agreed at an October summit in Trump's presence, after a Thai soldier was maimed by a landmine that Bangkok said was newly laid by Cambodia, which rejects the accusation.
The three days of clashes have taken a heavy toll on civilians, with nine people killed in Cambodia, including an infant, and 46 people wounded, according to its government. Five Thai soldiers had been killed in the fighting and 68 people were wounded, the Thai army said.
Hundreds of thousands of people have been evacuated from border areas, though some people have chosen not to leave.
