Prime Minister Hun Sen inaugurated two border markers with Vietnam over the weekend, including one in Ratanakkiri province close to where some 40,000 hectares in land concessions were revealed last week to be controlled by the Vietnamese military.

Four economic land concessions (ELCs) near the O’Yadav border checkpoint, where Hun Sen and his Vietnamese counterpart, Nguyen Tan Dung, presided over the ceremony on Saturday, are linked through their chairmen to the Vietnamese Army’s Corps 15, according to an investigation by the Cambodia Daily.

The concessions – Veasna Investment, Chea Chanrith, Rama Khmer and Dai Dong Duong – cover almost 40,000 hectares in Ratanakkiri, with three of the chairmen of the companies holding the leases also serving as commanders of Corps 15 units, according to the report.

The revelation seemingly validated the concerns of critics of the government’s policy on the border, prompting opposition Cambodia National Rescue Party president Sam Rainsy to warn that leasing such large tracts of land to a foreign military was “a serious threat to Cambodia’s national sovereignty and territorial integrity”.

“Granting 99-year land concessions covering tens of thousands of hectares in Ratanakkiri province, in an area adjacent to the border with Vietnam, to the Vietnamese army is a grave error,” he said in a post on Facebook.

“Each year, land and forest concessions granted by our government to foreign companies bring to Cambodia less than $10 million, while Vietnam collects up to $800 million from the timber trade,” he added.

Between February 2011 and August 2012, the four concessions were quietly transferred to the control of Do Van Sang, commander of Company 75, Pham Van Giang, commander of Company 72, Tran Quang Hung, commander of Company 74, and Nguyen Canh Quang, chairman of Aphivat Caoutchouc 72 Oya Dav Co, Ltd, which acquired the Chea Chanrith concession, according to the Daily.

Var Kimhong, the senior minister in charge of border affairs, said yesterday that he doubted that the government had leased the land to the Vietnamese companies, without offering any contradictory evidence.

A committee tasked with assessing ELCs is due to probe the Ratanakkiri concessions in the coming weeks, he added.

Hun Sen on Saturday said his government “would work with the Vietnamese government to guarantee our people have a proper border as a real international borderline”.

“The border must reflect the real situation of people living along the border to end [the dispute],” he added.

Yesterday Hun Sen presided over the inauguration of another border post in Takeo province. A joint commission for demarcating the border, chaired by Kimhong, was set up on December 17.

Chhay Thy, provincial coordinator for the rights group Adhoc, said the acquisition of the concessions by the Vietnamese companies had led to a spike in illegal logging, which was only slowed because of protests from Cambodians living in the area.