Outspoken opposition lawmaker Um Sam An yesterday declared he had discovered the “official maps” that should be used to demarcate Cambodia’s boundary with Vietnam in the United Nations’ New York library, a claim swiftly dismissed by the government.

Sam An, who has accused the government of ceding land by using maps favourable to Vietnam, said the charts were the Bonne 1/100,000-scale ones printed by the French colonial Indochinese Geographical Service.

He said they were deposited at the UN library on October 4, 1954 – after an international conference in Geneva on Indochina territorial integrity – making them the official internationally recognised maps cited in Cambodia’s constitution.

They differ from maps recently loaned by the UN to Cambodia, which were based on the UTM coordinate system, Sam An said, adding the government should review the demarcation in light of the discovery.

But Va Kimhong, senior minister in charge of border affairs, dismissed the idea, saying the government’s recent efforts to verify its demarcation maps had settled the issue.