The U.N.'s highest court has ordered both Cambodia and Thailand to immediately withdraw all troops and police from a newly declared demilitarized zone around an ancient Khmer temple on their border.

The International Court of Justice in The Hague also ruled Monday that both countries should allow observers from the Association of South East Asian Nations into the area to observe a cease-fire.

The case was brought by Cambodia, which wanted the court to order the withdrawal of all Thai troops from the area. However, the court went beyond that and declared the “provisional” demilitarized zone, saying both countries should remove their troops.

The two sides argued their cases before the 15 judges at The Hague at the end of May.

The ICJ ruled in 1962 that the 900-year-old Preah Vihear Hindu temple was located in an area under Cambodian sovereignty.

Thailand accepted the decision, but laid claim to more than four square kilometers of land surrounding the temple.

Tensions have mounted since 2008, when the United Nations Educational, Scientific and Cultural Organization listed the temple as a World Heritage Site. Thai and Cambodian forces clashed for several days in the area in February, killing 10 people and forcing thousands of villagers to flee.

At least 18 others were killed during clashes at another border site in April.

In late June, Thailand withdrew from the World Heritage Convention and World Heritage Committee, saying the move was made to protect the country's sovereignty.