Thailand's ambassador to the United Nations accused Cambodia yesterday of employing diplomatic "guerrilla tactics" in a dispute over an ancient temple to try to redraw the shared 800-kilometre border.

The ambassador, Don Pramudwinai, said the Cambodians were using a century-old map of the disputed temple, drawn up when Cambodia was a French colony, in a broader plan to gain more territory.

"Sometimes our sincere friendship has prompted us to overlook our neighbours' ultimate motive," the ambassador told a Thai radio station, speaking from New York, where Cambodia has asked the United Nations Security Council to help resolve the dispute.

"In this case, they are using guerrilla tactics to ambush us," he said. About 4.7 square kilometres of land around the temple form one of 16 sites along the border that involve territorial claims between the two nations.

Hundreds of Thai and Cambodian soldiers remained camped at the 900-year-old temple, perched high on an escarpment in the Dangrek Mountains, which form part of the border.

On Tuesday, Cambodia's foreign minister, Hor Namhong, said international mediation was needed because the two nations were in an "imminent state of war."

Sovereignty over the 11th century temple, Preah Vihear, has been in dispute since the withdrawal of the French in the 1950s. Although it is easily accessible only from the Thai side, the International Court of Justice awarded sovereignty over the temple to Cambodia in 1962.

Despite the ambassador's rhetorical escalation, Thailand's prime minister, Samak Sundaravej, played down the dispute yesterday, predicting tensions would ease after the general election in Cambodia Sunday.

"After the elections, they will soften their stance and talks will be easier," he said.

"Everything has been done for the July 27 poll and I need to keep quiet so as not to discredit Prime Minister Hun Sen," he said, referring to the Cambodian leader.

The two sides met Monday, but failed to resolve the dispute, which began earlier this month when the United Nations Cultural Organization listed the temple as a World Heritage Site, acting on an application from Cambodia and using a map supplied by Cambodia.

The two nations were taking part yesterday in a meeting of the Association of Southeast Asian Nations in Singapore, where diplomats from neighbouring nations urged them to find a peaceful solution.

But the standoff was inflaming nationalist feelings in both countries that have flared into local violence in the past. Opposition politicians in both countries are accusing their governments of being soft in their dealings over the temple.

The temple, perched high on a bluff on a disputed patch of border, may be the prize. But the conflict has also created a secondary, more prosaic target: an embattled government in Bangkok, where the opposition is using the historical dispute and nationalist fervour as weapons.

The fires of nationalism have spread in both nations over the past few weeks. Old grievances have flared, and troops and heavy weapons have been mobilized in the mists above the jungle. Over the weekend, truckloads of reinforcements from both countries were seen heading toward the temple, called Preah Vihear.

Tense moments have been reported when weapons were aimed within the temple complex. The prime ministers of both nations have exchanged stern notes, hardening their positions.

The Cambodian government has taken its complaint to the United Nations, saying that Thai troops have intruded onto its territory. The Thai prime minister, Samak Sundaravej, insists that the area is Thai.

Neither government appears to want a war, and there were plans for the countries' defence ministers to talk Monday.

The conflict comes at a delicate political time for both countries. Thailand has its slow-burning political crisis, and nationalism is looming as a factor in Cambodia's Sunday general election as well.

But in Bangkok, the political damage has already been done: The resignation of a cabinet minister, a censure debate in parliament and accusations of national betrayal have further weakened a shaky, ineffective government.

"The Democrats have used this quite dishonestly to get at the current government," said Chris Baker, a British historian of Thailand, speaking of the main opposition party. "This, of course, is a very dangerous game. A troop buildup is a very dangerous game. It's a very stupid way for Thailand to deal with an important neighbour."

Sovereignty is a volatile issue in a region where dominance has shifted over the centuries among empires in what are now Vietnam, Laos, Cambodia and Thailand. "The dark side of nationalism is as dangerous as ever," said Thongchai Winichakul, a historian and author of Siam Mapped: A History of the Geo-Body of a Nation (Honolulu: University of Hawaii Press, 1994).

Cambodia, which has been annexed throughout history by its neighbours on both its eastern and western borders, is particularly sensitive, and its temples are a source of national pride. They symbolize its last period of greatness, under the Angkorean kings, which ended with a Thai invasion in the 15th century.

Just five years ago, mobs in Cambodia burned down the Thai Embassy because of rumours that a Thai actress had claimed Thai sovereignty over Cambodia's greatest temple, Angkor Wat.

The catalyst of the latest confrontation seemed mild enough: the naming of the Preah Vihear temple as a World Heritage Site, a designation that is meant to preserve historical monuments, not to call out armed soldiers.

The temple itself, built between the ninth and 11th centuries, is unlike any other. It is an ornate, sagging ruin of broken pillars and sweeping roofs that stands alone on a finger of rock, high above the forests of the Dangrek Mountains. It was consecrated to the Hindu god Shiva when it was built, but, like other temples in the Angkorean period, was converted to Buddhist use.

Questions of sovereignty are complicated by the temple's location at the top of a 500-metre cliff. It is almost inaccessible from Cambodia, but it is reachable through Thailand by a comfortable drive over a paved road.

On June 17, UNESCO placed the temple on its list of protected monuments, or World Heritage sites. It was responding to a bid from Cambodia that included a disputed map drawn up by French colonial rulers in 1907.

Legally, the temple has belonged to Cambodia since 1962, after a ruling by the International Court of Justice in the Hague. The French had left Indochina seven years before, and the temple had been occupied in the interim by Thai soldiers.

The Thais were forced to withdraw and the court's decision has rankled in Thailand ever since.

The validity of the French map and the court's logic have been questioned, and the focus is now on 4.7 square kilometres around the temple that were not specifically covered in the ruling.

In a strangely passive response last month, the Thai government failed to insist on joining Cambodia as a bidder for the UNESCO designation and signed off on the questionable map that Cambodia presented.

This was fuel enough for the Thai opposition, which says, without presenting evidence, that a backroom deal had been struck and that the man behind it was the country's most prominent wheeler dealer, former prime minister Thaksin Shinawatra.

Thaksin, who was deposed in a coup in 2006, remains a player in business and politics, and he does have financial interests in Cambodia. The man who let Cambodia's bid slip through -- and who was forced to resign as a result -- was foreign minister Noppadon Pattama, once Thaksin's personal lawyer.

The embattled prime minister, Samak, is also seen by his critics as Thaksin's proxy and, under pressure from the opposition, he has begun talking tough.

Having earlier called the nationalist protesters crazy, Samak sounded a nationalist note last Friday, saying that the Cambodian presence at the temple "is a continued violation of Thailand's sovereignty and territorial integrity."

The Dangrek Mountain range and the high plains in Thailand that lie beyond it are home to dozens of lesser temples in Khmer style, including two in Thailand that Cambodia laid claim to in 2003.

Experts say there are 15 more overlapping locations along the nations' 800-kilometre border that need to be resolved.

But Preah Vihear, in its majesty and geographical ambiguity, has been the symbol for both sides' claims of dominance. "The Preah Vihear temple is part of a wounded history of Thailand and Cambodia," said Charnvit Kasetsiri, a historian at Bangkok's Thammasat University.

That history -- as the troops and heavy weapons deployed at the temple show -- has not yet receded into the past.