Border tensions between Thailand and Cambodia have again flared after Cambodian Prime  Minister Hun Sen accused Thai troops of entering his country. The confrontation follows talks between the foreign ministers of both countries over the land surrounding an ancient temple. As Ron Corben reports from Bangkok, the Thai government says it will defend its territory if Cambodia uses force.

Cambodia's Prime Minister Hun Sen said Thai troops had entered his country and on Tuesday issued an ultimatum for them to leave or risk conflict.

The once dormant dispute over 900-year-old Preah Vihear turned tense earlier this year after Thailand granted Cambodia the right to have the temple recognized as a United Nations World Heritage site. The temple sits on Cambodia's side of the border, but the main access route to it is in Thailand.

A public outcry in Thailand caused both governments to send troops to the area.

On Monday, the two countries' foreign ministers met to resolve the dispute over the border area, but the talks were inconclusive.

The Thai Foreign Ministry warned that if Cambodia resorted to force, Thailand would exercise its right to self defense. But the ministry also called for issue to be settled peacefully.

The Thai military and Prime Minister Somchai Wongsawat met Tuesday to discuss the matter. Mr. Somchai proposed a joint committee to oversee any troop withdrawal.

Shortly before Cambodia's noon deadline for the Thai troops to move, the Cambodian army chief said all were back in Thai territory.

Panitan Wattanayagorn, a political scientist at Chulalongkorn University in Bangkok, says the two governments need to resume talks to avoid violence.

"The Thai military, it's quite clear they're not going to move back from the claimed territory. If the Cambodians want them to move out from these areas they may have to use force," said Panitan.

The countries have long disputed the ownership of the temple and the border. In 1962, the International Court of Justice granted sovereignty to Cambodia, but adjacent land remained under Thai control.

The dispute puts further pressure on the Thai prime minister. For weeks, opposition groups have occupied the main government office building, demanding the ouster of Mr. Somchai and new elections.