BANGKOK/PHNOM PENH — Cambodian and Thai soldiers clashed in several areas along their border on Thursday, leaving at least 11 civilians dead, in a major escalation of a row between the two neighbors.

Both nations accused each other of starting the military clashes and have downgraded their diplomatic relations since Wednesday. Thailand also sealed all land border crossings with Cambodia.

The first clash on Thursday morning happened in an area near the ancient Ta Muen Thom temple along the border. Both governments say they have to respond to the other's actions.

The Thai army said its forces heard a drone before seeing six armed Cambodian soldiers moving closer to Thai military positions at the border. It said Thai soldiers tried to shout at them to defuse the situation, but the Cambodian side started to open fire.

Cambodia's Defense Ministry, however, said Thailand deployed a drone first before opening fire, and that Cambodia "acted strictly within the bounds of self-defense, responding to an unprovoked incursion by Thai troops that violated our territorial integrity".

Cambodian Prime Minister Hun Manet wrote to the president of the UN Security Council seeking an urgent meeting "to stop Thailand's aggression".

Thailand's Foreign Ministry accused Cambodia of attacking both military and non-military sites in Thailand, including a hospital.

Thailand's health minister said as many as 11 Thai civilians and one soldier have been killed in the latest outbreak. The Thai army said the most casualties occurred in Si Sa Ket Province, where six people were killed after shots were fired at a gas station. At least 14 people were injured in three border provinces. Cambodia released no details on deaths or injuries on its side.

On Wednesday, Thailand withdrew its ambassador to Cambodia and expelled the Cambodian ambassador to protest a mine blast that wounded its soldiers.

Thai authorities claimed the mines were newly laid along paths that both sides had agreed were supposed to be safe. They said the mines were not of a type employed by Thailand's military.

Cambodia rejected Thailand's account as "baseless accusations", pointing out that many unexploded mines and other ordnances are the legacy of 20th-century wars and unrest.

Cambodia also downgraded diplomatic relations, recalling all Cambodian staff on Thursday from its embassy in Bangkok.

The international community has stepped up its efforts in calling for dialogue since the latest conflict flared up.

Anwar Ibrahim, the prime minister of Malaysia, which currently chairs the Association of Southeast Asian Nations, called on its fellow members, Thailand and Cambodia, to "stand down".

"The least we can expect is for them to stand down and hopefully try to enter into negotiation," said Anwar.

Dialogue urged

China expressed deep concerns over the latest situation, calling on the two sides to solve their issues properly through dialogue and consultation.

Speaking at a regular news briefing in Beijing, Foreign Ministry spokesman Guo Jiakun said that Thailand and Cambodia are both friendly neighbors of China and important members of ASEAN.

He emphasized that resolving their differences through dialogue and consultation is in the fundamental and long-term interests of all parties involved.

"We are deeply concerned about the current developments and hope that the two sides will resolve their issues properly through dialogue and consultation," Guo said.

The spokesman said from the perspective of the common interests and aspirations of countries in the region, China has upheld a fair and impartial position.

"China has been and will continue to facilitate peace and dialogue in its own way, playing a constructive role in easing tensions and cooling down the situation," Guo said.

Mo Jingxi in Beijing contributed to this story.

Agencies - Xinhua