Both Thailand and Cambodia claim territory that surrounds the temple
Cambodia has asked the UN Security Council for an emergency meeting to resolve a tense stand-off with Thailand near the site of an ancient temple.
For the past week, more than 500 Thai and 1,000 Cambodian soldiers have been stationed on opposite sides of disputed land near Preah Vihear temple.
The standoff began when the UN approved Cambodia's application to have the complex named a World Heritage Site.
Bilateral talks on Monday failed to resolve the row.
A quickly-arranged foreign ministers' lunch on Tuesday on the sidelines of the Asean regional meeting in Singapore also failed to produce any agreement, officials said.
Cambodia is seeking third-party mediation, but Thailand wants to resolve the dispute at a bilateral level, officials from both sides said.
At the heart of the dispute is a 4.6 sq km (1.8 sq mile) area around the 11th Century temple.
The International Court of Justice awarded Preah Vihear to Cambodia in 1962, but areas around it remain the subject of rival territorial claims.
Earlier this month Unesco listed the temple as a Cambodian World Heritage Site, reigniting nationalist tensions, particularly in Thailand.
Opposition forces there have been using the issue to attack the government - which initially backed the heritage listing. Foreign Minister Noppadon Pattama has resigned over the issue.
Thai troops moved into the area more than a week ago, after Cambodian guards arrested three Thai protesters, and since then both sides have increased their military presence.
The two nations attempted to reach an agreement on Monday, during bilateral talks on the opening day of the Asean regional summit in Singapore.
But officials said the discussions stalled over which maps should be used to settle ownership.
Singapore Prime Minister Lee Hsien Loong told the Asean meeting that both nations had promised to exercise "utmost restraint" and abide by international laws to resolve the issue amicably.
Shortly after that, Cambodia appealed to the United Nations to resolve the row "in order to avoid armed confrontation".
The dispute comes at a difficult time for Thailand, which is due to take over the rotating chairmanship of Asean next week.