Thailand’s army on Monday (Dec 29) accused Cambodia of violating a newly signed ceasefire agreement, reached after weeks of deadly border clashes, by flying more than 250 drones over its territory.

Thailand and Cambodia agreed to the “immediate” ceasefire on Saturday, pledging to end renewed border clashes that killed dozens of people and displaced more than a million this month.

But the fresh allegation from Bangkok and its threat to reconsider releasing Cambodian soldiers held by Thailand left a sustained truce in doubt - even as the two nations’ foreign ministers wrapped up two days of talks hosted by China aimed at rebuilding trust and improving relations.

The Thai army said Monday “more than 250 unmanned aerial vehicles were detected flying from the Cambodian side, intruding into Thailand’s sovereign territory” on Sunday night, according to a statement.

“Such actions constitute provocation and a violation of measures aimed at reducing tensions, which are inconsistent with the joint statement agreed” during a bilateral border committee meeting on Saturday, it added.

The reignited fighting spread to nearly every border province on both sides, shattering an earlier truce for which US President Donald Trump took credit.

Under the agreement signed on Saturday, the Southeast Asian neighbours agreed to cease fire, freeze troop movements and cooperate on demining efforts and combatting cybercrime.

They also agreed to allow civilians living in border areas to return home as soon as possible, while Thailand was to return 18 Cambodian soldiers captured in July within 72 hours, if the ceasefire held.

Cambodian Foreign Minister Prak Sokhonn said in remarks aired on state television on Monday that the two sides had discussed the incident and agreed to investigate and “resolve it immediately”.

Prak Sokhonn described it as “a small issue related to flying drones seen by both sides along the border line”.

Thai army spokesman Winthai Suvaree, however, said in its statement that the drone activity reflected “Cambodia’s continued provocative actions and hostile stance toward Thailand”, which could affect the security of military personnel and civilians in border areas.

Thailand’s army “may need to reconsider its decision regarding the release of 18 Cambodian soldiers, depending on the situation and the behaviour observed”, the statement added.

While both sides agreed Saturday to stop fighting, they will still need to resolve the demarcation of their border.

The conflict stems from a territorial dispute over the colonial-era demarcation of the 800km Thai-Cambodian border, where both sides claim centuries-old temple ruins.

China had earlier said ⁠in a communique with the two countries on Monday that Thailand and Cambodia plan to rebuild mutual trust and gradually consolidate ⁠a ceasefire.

Thailand and Cambodia’s top diplomats had travelled to the Chinese province of Yunnan for trilateral talks with Chinese Foreign Minister Wang Yi to discuss the border situation on Sunday and Monday.

In a meeting with his Thai and Cambodian counterparts, Wang called the ceasefire “hard-won”, and urged the two nations not to abandon it halfway or allow fighting to resume.

“Discussions between the three parties were beneficial and constructive, and an important consensus was reached,” Wang had said, according to a statement released by his ministry, which did not mention the Association of Southeast Asian Nation’s (ASEAN) role in facilitating a ceasefire.

Thailand and Cambodia will “rebuild political mutual trust, achieve a turnaround in relations, and maintain regional peace”, according to a joint communique released by China’s official Xinhua news agency.

Thai and Cambodian defence officials also joined the talks in China.

Prak Sokhonn had said he believed the latest ceasefire would last and would create an environment for both countries to work on their relations and resume the previously agreed-upon ways to settle their differences, according to a Chinese interpreter.

Cambodia also said Monday it had called on Thailand to join another bilateral meeting in Cambodia in early January to “to discuss and continue survey and demarcation work” at the border.

Thai Foreign Minister Sihasak Phuangketkeow had also expressed hopes for peace with neighbouring countries, the interpreter said.

- Agencies