Thai and Cambodian soldiers exchanged on their border fire for a second day today in a brief clash that killed a Thai soldier, the latest flare-up in a long-running feud over land around an 11th-century temple.
Southeast Asia's regional grouping, of which both Thailand and Cambodia are members, said the deteriorating situation was undermining confidence in the region and would affect its economic recovery.
The Thai soldier was killed, and four were wounded, in a two-square-mile disputed area around the 900-year-old Preah Vihear temple, a jungle-clad escarpment claimed by both countries, said Thai army spokesman Colonel Sansern Kaewkamnerd.
The neighbours fought with rocket-propelled grenades and guns for about 25 minutes from 6:15am local time before reaching a ceasefire in the early afternoon and agreeing not to reinforce troops, the spokesman said.
That followed an intense two-hour clash yeseterday in which three Cambodians, including two soldiers, and a Thai villager were killed, the first fatalities in the militarised border area since a Thai soldier was shot dead on 31 January 2010.
Cambodian government spokesman Phay Siphan said one of the Cambodians killed yesterday was a tourist visiting the temple overlooking northern Cambodia. He said 10 Cambodian soldiers were wounded, but there were no fatalities on today.
The United States has urged both sides to show restraint.
The fighting is the latest flare-up in on-again off-again tension between the neighbours and could inflame passions among Thai pro-establishment "yellow shirt" protesters demanding Prime Minister Abhisit Vejjajiva take a tougher line against Cambodia.
The Thai Foreign Ministry accused Cambodia of engaging in "an act of aggression" in "violation of Thai sovereignty and territorial integrity". Cambodia accuses Thailand of invasion and filed a complaint with the UN Security Council.
The Thai government said 3,000 civilians were evacuated during yesterday's fighting.
The clashes come after a Cambodian court on Tuesday handed down jail terms of six and eight years to two Thai activists found guilty of trespassing and spying in the border region, a verdict that has angered some in Thailand.
The temple, known as Preah Vihear in Cambodia and Khao Phra Viharn in Thailand, sits on land that forms a natural border and has been a source of tension for generations.
The International Court of Justice awarded it to Cambodia in 1962 but the ruling did not determine the ownership of the scrub next to the ruins, leaving considerable scope for disagreement.
The area is remote with only scattered villages on the Thai side and little development on the Cambodian side.
The secretary-general of the Assocition of South East Asian Nations (ASEAN) caled for calm and said both sides must return to negotiations.
"The situation has escalated into open conflict. And that will definitely affect our economic development, confidence in our region, and tourism and prospects for foreign investment, which have just been picking up in light of the world economic recovery," Surin Pitsuwan said in a statement.
Surin, a former Thai foreign minister, said he had been in touch with both sides who he understood welcomed ASEAN mediation.