Where do you draw the line?

Demarcation of the Thai-Cambodian border remains a sensitive issue, write Piyaporn Wongruang and Thanida Tansubhapol

Although Thailand and Cambodia have worked to demarcate their boundaries for more than 100 years, they still have overlapping areas. For example, the disputed maritime area in the Gulf of Thailand alone covers about 26,000 square kilometres.

The latest problem involves the Preah Vihear temple, on the border between Si Sa Ket province in Thailand and Preah Vihear province in Cambodia.

In Cambodia, the affair has been linked to the country's election next month, as securing World Heritage status for the site could boost the government's popularity with voters.

In Thailand, the issue is being stoked by nationalism stirred up by current political conflicts in Thailand.

The dispute has been taken up by the People's Alliance for Democracy as part of its campaign to remove the government from office.

Attempts to define the border between Thailand and Cambodia began when France, which controlled the Indochina region of Cambodia, Laos and Vietnam, sought to map the area.

According to a report by the International Court of Justice (ICJ), which ruled on the dispute over Preah Vihear in 1962, France and Thailand entered an agreement to determine the border for the first time in 1904.

They decided to use the watershed to define the border and, three years later, the two countries signed a boundary delineation agreement. Finally, a series of 11 maps defining most of the border was completed.

But these efforts have periodically triggered arguments, with Preah Vihear being a major site of contention. According to the same ICJ report, the original map did not conform to the watershed line.

The map had marked Cambodia's boundary behind the promontory where Preah Vihear sits.

The court said the map was acknowledged by Thailand without any veto and was in use for several years before Cambodia eventually took the case to the court. That led to the ICJ ruling in favour of Cambodia on the sovereignty of the temple in 1962.

Thai Foreign Minister Noppadon Pattama and Cambodian Deputy Prime Minster Sok An signed a joint statement on June 18 to allow Cambodia to apply for World Heritage status for the temple from Unesco. Given the border dispute, both countries must support a World Heritage bid.

There were reports that Cambodia had attempted to register the temple as a World Heritage site without Thailand's approval in 1991, but a Foreign Ministry source insisted that the first attempt was made in 2006. At that time, the boundary included the 4.6-square-kilometre disputed area which had not been demarcated.

Cambodia proposed it to the World Heritage Committee in 2006, but Thailand did not support the bid.

''Thailand categorically rejected it because the Cambodian side had used the old map [drawn in 1904 by France] which claimed the 4.6-square-kilometre area as part of its territory,'' the ministry source said.

Finally, Cambodia drew a new map excluding the area which has not been demarcated and this has been accepted by the Thai government.

But historian M.L. Walwipha Charoonroj, of Thammasat University's Thai Khadi Research Institute, said this agreement will not put an end to the issue.

''Thailand and Cambodia should work together to determine where the boundary line lies. This cannot be done by an administrative agency alone, as any such decision will be made with its nation's interests at heart,'' she said.

A high-level source working on the issue is concerned about the negative impact of the map on the temple.

As the temple is now being proposed separately from its surroundings, this devalues the site in archaeological terms, the source said.

But for the Foreign Ministry, the new map is seen as the best solution, as it covers only the temple, and not the overlapping zone. It means that Thailand does not lose any of its territory, the ministry said.

The demarcation in the new map also conforms to a Thai cabinet resolution in 1962 which ruled the watershed lines are the border line under international law, it added.