Thailand and Cambodia exchanged heavy artillery for the second consecutive day, marking the worst escalation of tension between the neighbours in more than a decade.

The ongoing clash has left 15 people dead.

Thailand's Second Army Region reported clashes from before dawn in Ubon Ratchathani and Surin provinces and said Cambodia had used artillery and Russian-made BM-21 rocket systems, reported Bangkok Post.

According to reports, 100,000 people have been displaced from he conflict-hit regions on the Thailand side.

Some 1,500 families in Cambodia's Oddar Meanchey province have been evacuated, BBC reported.

Malaysia appeals for peace

Meanwhile, Malaysian PM Anwar Ibrahim has appealed PMs of both nations to reach a ceasefire.

He wrote on Facebook: "This evening, I spoke with both the Prime Minister of the Kingdom of Cambodia, Hun Manet, and the Acting Prime Minister of the Kingdom of Thailand, Phumtham Wechayachai, expressing Malaysia’s deep concern over the escalation of tensions along their border."

He further said: "In our conversations, in Malaysia's capacity as ASEAN Chair for 2025, I appealed directly to both leaders for an immediate ceasefire to prevent further hostilities and to create space for peaceful dialogue and diplomatic resolution."

US expresses grave concern over the escalation of tensions

The United States Department of State expressed concern over the ongoing escalation in tension in the region.

"The United States is gravely concerned by reports of the escalating fighting along the Thailand-Cambodia border," the US Department of State said in a statement.

The Department said: "We are particularly alarmed by reports of harm to innocent civilians. We express our deepest condolences on the loss of life.  We strongly urge the immediate cessation of attacks, protection of civilians, and peaceful settlement of disputes."

The dispute dates to 1953 when France first mapped the border, but tensions resurfaced in May after the death of a Cambodian soldier in a border skirmish.

UN Secretary-General António Guterres is “following with concern” reports of the clashes, his Deputy Spokesperson Farhan Haq told journalists in New York.

“The Secretary-General urges both sides to exercise maximum restraint and address any issues through dialogue and in a spirit of good neighbourliness, with a view to finding a lasting solution to the dispute,” he said.