The Thai government said it didn't support the World Heritage Convention, the latest flare-up in a border dispute with Cambodia.
Irina Bokov, director general of the U.N. Educational, Scientific and Cultural Organization, said her agency was an "indispensable tool" for international cooperation. Thailand, she said in a statement, should "carefully consider its future course of action" regarding the convention.
Cambodia has called in the International Court of Justice again to weigh in on a dispute surrounding access and ownership of land near the 900-year-old Preah Vihear temple, declared a World Heritage site in 2008.
The ICJ in 1962 ruled the temple on the site was on Cambodian land but some access to the mountaintop site passes through Thai territory, a route that Thai troops occasionally seal off.
Fighting has flared in the area within the past several years. Cambodia said it would keep its troops positioned on the border.