A group of 15 civil society organisations yesterday sent open letters to all 123 members of the National Assembly asking them to help get a controversial 2005 supplemental border treaty with Vietnam cancelled.

Rong Chhun, a unionist part of the Cambodian Watchdog Council, said yesterday that the treaty had caused Cambodia to lose territory to Vietnam.

Chhun recently led a delegation to the border in Svay Rieng province’s Romduol district.

“We found many small border marker posts planted in our territory. It is contrary to what Prime Minister Hun Sen claimed, that there would be no planting in just [our land],” but rather on both sides.

While the opposition backed the group’s proposal that the Constitutional Council be asked to cancel the treaty, senior ruling party lawmaker Chheang Vun said that “civil society cannot order the National Assembly”.

Government spokesman Phay Siphan said the request was “politically motivated” and that the treaty guarantees the rights of both countries to review border affairs.