Cambodia wants an "immediate ceasefire" with Thailand, the country's envoy to the United Nations has said, after the neighbors traded deadly strikes for a second day.
"Cambodia asked for an immediate ceasefire - unconditionally - and we also call for the peaceful solution of the dispute," said Cambodia's ambassador Chhea Keo following a closed meeting of the Security Council attended by Cambodia and Thailand.
None of the other attendees spoke to reporters.
Earlier, Thailand declared martial law in eight districts bordering Cambodia following a second day of violent clashes that has led to the death of at least 15 people.
Commander of the military's Border Defense Command in the provinces of Chanthaburi and Trat, Apichart Sapprasert, said "martial law is now in effect" in seven districts of Chanthaburi and one district of Trat.
While Thailand's acting Prime Minister Phumtham Wechayachai warned that cross-border clashes with Cambodia "could develop into war", as the countries traded deadly strikes for a second day.
Thailand and Cambodia exchanged heavy artillery fire as their worst fighting in more than a decade stretched into a second day, despite calls from the region and beyond for an immediate ceasefire in an escalating border conflict that has killed at least 16 people.
"We have tried to compromise as we are neighbours, but we have now instructed the Thai military to act immediately in case of urgency," said Mr Wechayachai.
"If the situation escalates, it could develop into war - though for now, it remains limited to clashes," he told reporters in Bangkok.
Thailand's military reported clashes from before dawn in the Ubon Ratchathani and Surin provinces and said Cambodia had used artillery and Russian-made BM-21 rocket systems.
More than 138,000 people have been evacuated from Thailand's border regions, its health ministry said, reporting 15 fatalities - 14 civilians and a soldier - with a further 46 wounded, including 15 troops.
Cambodia has stayed tight-lipped about its casualty numbers, but AFP journalists saw four wounded soldiers and three civilians receiving treatment at a hospital in Oddar Meanchey.
"Cambodian forces have conducted sustained bombardment utilising heavy weapons, field artillery, and BM-21 rocket systems," the Thai military said in a statement.
"Thai forces have responded with appropriate supporting fire in accordance with the tactical situation."
Both sides blamed each other for starting the conflict at a disputed border area, which quickly escalated from small arms fire to heavy shelling in at least six locations 209km apart along a frontier where sovereignty has been disputed for more than a century.
Reuters journalists in Surin province reported hearing intermittent bursts of explosions, amid a heavy presence of armed Thai soldiers along roads and gas stations in the largely rural area.
A Thai military convoy, including around a dozen trucks, armoured vehicles and tanks, cut across provincial roads ringed by paddy fields and moved toward the border.
The fighting erupted yesterday just hours after Thailand recalled its ambassador to Phnom Penh the previous night and expelled Cambodia's envoy, in response to a second Thai soldier losing a limb to a landmine that Bangkok alleged had been laid recently by rival troops.
Cambodia has dismissed that as baseless.
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Death toll rises
The Thai death toll rose to 15, 14 of them civilians, according to the health ministry. It said 46 people were wounded, including 15 soldiers.
Cambodia's national government has not provided details of any casualties or evacuations of civilians.
A government spokesperson did not immediately respond to a request for comment on the latest clashes.
Meth Meas Pheakdey, spokesperson for the provincial administration of Cambodia's Oddar Meanchey province, said one civilian had been killed and five were wounded, with 1,500 families evacuated.
Thailand had positioned six F-16 fighter jets in a rare combat deployment, one of which was mobilised to strike Cambodian military targets, among measures Cambodia called "reckless and brutal military aggression".
The United States, a long-time treaty ally of Thailand, called for an "immediate cessation of hostilities, protection of civilians and a peaceful resolution".
Malaysian Prime Minister Anwar Ibrahim, the chair of the Association of Southeast Asian Nations, of which Thailand and Cambodia are members, said he had spoken to leaders of both countries and urged them to find a peaceful way out.
"I welcome the positive signals and willingness shown by both Bangkok and Phnom Penh to consider this path forward. Malaysia stands ready to assist and facilitate this process in the spirit of ASEAN unity and shared responsibility," he said in a social media post.
Don't travel to border zone, Irish citizens told
The Department of Foreign Affairs has advised Irish citizens "against all travel to the entirety of the border region between Thailand and Cambodia".
It said that "border crossings are subject to restrictions and closures and there may be a possibility of disruption to air travel between the two countries.
"We strongly advise citizens against any attempt to approach or cross the border.
"The situation remains very fluid and Irish citizens in Thailand - or intending to visit the country - should pay close attention to authoritative sources of information and advice, and remain vigilant at all times."
