WASHINGTON: US President Donald Trump said on Saturday (Jul 26) that the leaders of Cambodia and Thailand had agreed to meet immediately to quickly work out a ceasefire, as he sought to broker peace after three days of fighting along their border.

Thailand's acting prime minister, Phumtham Wechayachai, thanked Trump and said Thailand"agrees in principle to have a ceasefire in place" but "would like to see sincere intention from the Cambodian side".

Phumtham was responding in a Facebook post to a series of social media posts by Trump during a visit to Scotland. Trump said he had spoken to Cambodian Prime Minister Hun Manet and Phumtham and warned them that he would not make trade deals with either if the border conflict continued.

"Both parties are looking for an immediate Ceasefire and Peace," Trump wrote as he gave a blow-by-blow account of his diplomatic efforts.

Phumtham also said he had asked Trump"to convey to the Cambodian side that Thailand wants to convene a bilateral dialogue as soon as possible to bring forth measures and procedures for the ceasefire and the eventual peaceful resolution of the conflict".

More than 30 people have been killed and more than 130,000 people displaced in the worst fighting between the Southeast Asian neighbours in 13 years.

Before Trump spoke to the two leaders, clashes on the Thai-Cambodian border persisted into a third day and new flashpoints emerged as both sides said they had acted in self-defence in the border dispute and called on the other to cease fighting and start negotiations.

UN Secretary-General Antonio Guterres is deeply concerned by the clashes and"urges both sides to immediately agree to a ceasefire and to address any issues through dialogue," Deputy UN spokesperson Farhan Haq said in a statement.

Haq said Guterres"condemns the tragic and unnecessary loss of lives" and "remains available to assist in any efforts towards a peaceful resolution of the dispute".

Trump offered no details on the ceasefire negotiations he said Thailand and Cambodia had agreed to hold.

The White House did not immediately respond to questions on the timing and venue for talks and the Thai and Cambodian embassies in Washington also did not immediately respond.

There were clashes early on Saturday, both sides said, in the Thai coastal province of Trat and Cambodia's Pursat Province, a new front more than 100km from other conflict points along the long-contested border.

The countries have faced off since the killing of a Cambodian soldier late in May during a brief skirmish. Troops on both sides of the border were reinforced amid a full-blown diplomatic crisis that brought Thailand's fragile coalition government to the brink of collapse.

As of Saturday, Thailand said seven soldiers and 13 civilians had been killed, while Cambodia said five soldiers and eight civilians had been killed.

Trump's direct involvement followed US calls for restraint on both sides. He said he spoke to each leader and relayed messages back and forth.

"They have agreed to immediately meet and quickly work out a Ceasefire and, ultimately, PEACE!" Trump wrote, saying both countries wanted to get back to the"trading table".

He has sought to reach separate deals with dozens of countries by Aug 1 in response to his announcement of wide-ranging tariffs on imports to the US.

"When all is done, and peace is at hand, I look forward to concluding our trading agreements with both!" Trump said.

Malaysian Prime Minister Anwar Ibrahim, chair of the ASEAN regional bloc, said he would continue to push a ceasefire proposal. Cambodia has backed Anwar's plan, while Thailand has said it agreed with it in principle.

SECURITY COUNCIL MEETING

Thailand's UN ambassador told a Security Council meeting on Friday that soldiers had been injured by newly planted land mines in Thai territory on two occasions since mid-July – claims Cambodia has strongly denied – and said Cambodia had then launched attacks on Thursday morning.

On Saturday, Cambodia accused Thailand of"a deliberate, unprovoked, and unlawful military attack" and said "military preparations reveal Thailand's intent to expand its aggression and further violate Cambodia's sovereignty".

It called for the international community to condemn Thailand's"aggression" and prevent an expansion of its military activities, while Bangkok says it wants to resolve the dispute bilaterally.

Southeast Asia expert Gregory Poling of Washington's Center for Strategic and International Studies said it would be positive if Trump could help speed up ceasefire talks, but cautioned:

"Neither Cambodia nor Thailand – or their publics – will appreciate the threat to weaponise trade to make it happen. And if they do reach a ceasefire and either or both still don't get a trade deal before Aug 1, they are likely to view it as a US betrayal."

Thailand and Cambodia have bickered for decades over undemarcated points along their 817km land border, with ownership of the ancient Hindu temples Ta Moan Thom and the 11th century Preah Vihear central to the disputes.

Preah Vihear was awarded to Cambodia by the International Court of Justice in 1962, but tension escalated in 2008 after Cambodia attempted to list it as a UNESCO World Heritage site, and skirmishes over several years brought at least a dozen deaths.