Bangkok - Cambodian soldiers on Tuesday detained three Thai protestors, including one Buddhist monk, who had crossed the border to demonstrate against the listing of Preah Vihear temple as a UN World Heritage Site despite Thailand's opposition.

State-run Thai TV PBS said the three men, identified as Phicharn Thapsorn, 35, Chanikarn Singnok, 64, and Buddhist Monk Khamphor, were detained by Cambodian soldiers Tuesday.

The group had crossed in to Preah Vihear province, Cambodia, from the Thai Khantalak district in Si Sa Khet province on Monday, the TV station said.

Preah Vihear temple, known as Phra Viharn in Thailand, was named a World Heritage Site at a UNESCO meeting in Quebec earlier this month, despite Thai opposition to the listing.

The ancient Hindu temple, perched on a 525-metre-high cliff on the Dangrek Mountain range that defines the Thai-Cambodian border, has been the source of a sovereignty dispute for decades.

An ownership spat between Cambodia and Thailand led to a suspension of diplomatic relations in 1958 and eventually ended up in The Hague for an international settlement in 1962. Cambodia won.

The temple reemerged as a source of bilateral tensions in 2006 when Cambodia first proposed listing the monument as a UNESCO World Heritage Site.

Thailand objected, and succeeded in blocking the subscription attempt in 2006 and 2007 on the grounds that parts of the temple compound were still subject to a border dispute.

Cambodia redrew the Preah Vihear inscription map this year, excluding the disputed territory. It was approved by the World Heritage Committee on July 7.

The Thai government at first backed the proposal, but then withdrew support when the issue became a political hot potato.

Residents of Si Sa Khet province, about 400 kilometres north-east of Bangkok, have been protesting the listing since early July, prompting Cambodia to shut access to the temple from the Thai side of the border. (dpa)