Fresh fighting has broken out along the Thailand–Cambodia border, prompting Thai air strikes and large-scale civilian evacuations, in the most serious escalation between the two neighbours since a ceasefire was agreed in July, the BBC reports.

The Royal Thai Army said it launched air attacks on Cambodian military positions after Thai troops came under fire on Monday morning, killing one Thai soldier and injuring four others. Thailand said the clashes occurred in its north-eastern provinces of Si Sa Ket and Ubon Ratchathani, opposite Cambodia’s Preah Vihear and Oddar Meanchey provinces.

Cambodia denied initiating the fighting and accused Thai forces of opening fire first. Cambodian officials said three civilians were injured in Oddar Meanchey in what they described as an attack by Thai troops, and that medical evacuations were under way.

The renewed violence has triggered mass displacement on both sides of the frontier. Thai military authorities said around 35,000 people had been moved to temporary shelters, while Cambodian officials reported large numbers of families fleeing border districts by tractors and trailers as shells and small-arms fire were reported in nearby areas.

According to the BBC, both governments accused each other of breaching a ceasefire brokered earlier this year by Malaysia, with support from Donald Trump. The truce followed a five-day conflict in July that killed at least 48 people and forced an estimated 300,000 civilians from their homes, marking the worst fighting between the two countries in years.

Thai military officials said rockets were fired from the Cambodian side during the latest clashes, a weapon system not seen since the ceasefire was agreed. A military spokesperson said the air force had targeted Cambodian positions in response to what Bangkok described as unprovoked fire the BBC added.

Phnom Penh rejected that account, saying it remained committed to the peace agreement and had acted in self-defence. Tensions had remained high in recent months despite the formal ceasefire, with Thailand accusing Cambodia of continuing to lay landmines that injured Thai soldiers, and Cambodia demanding the release of 18 soldiers captured by Thai forces during the July fighting.

Malaysia’s prime minister, Anwar Ibrahim, who helped mediate the earlier peace deal, called on both sides to show restraint and warned that renewed fighting risked unravelling fragile regional stability. He urged a return to diplomatic channels, saying long-standing disputes should not be allowed to escalate into cycles of confrontation.

The border dispute, rooted in unresolved colonial-era boundary demarcation, remains a persistent flashpoint for both countries, with no durable political settlement in sight.