PHNOM PENH: Cambodia's parliament stripped immunity from main opposition leader Sam Rainsy Monday, clearing the way for charges against him for uprooting markings at the border with neighbouring Vietnam.

"The National Assembly has lifted the parliamentary immunity of Sam Rainsy," said a statement from the legislative body.

The statement went on to say Sam Rainsy, currently abroad, had committed acts of "uprooting border posts between Cambodia and Vietnam, and inciting (people) to commit criminal offences" in southeastern Svay Rieng province.

The move permits court action against Sam Rainsy, who removed six markers at the border during a march in Svay Rieng last month, alleging that they were illegally placed by Vietnam.

Lawmakers from his eponymous Sam Rainsy Party (SRP) boycotted Monday's closed parliamentary vote and held aloft a map of Cambodia as they marched through the capital's streets, denouncing the decision as "political intimidation".

The French-educated former finance minister is the main rival to Prime Minister Hun Sen. He touts liberal democracy and human rights, while promising to raise wages and fight corruption.

Son Chhay, chief of the party's members of parliament, called the decision a "threat or intimidation against the party leader... (with) political intention to shut up the opposition party".

Vietnam condemned Sam Rainsy for uprooting the border posts, and asked Phnom Penh to protect the two nations? sensitive demarcation process.

Sam Rainsy has said he believed the border markers were erected unilaterally by Vietnamese authorities, and that villagers had removed similar posts in the area early this year.

Cambodia and Vietnam officially began demarcating their contentious border in September 2006, in a bid to end decades of territorial disputes.

The border row has sparked virulent anti-Vietnamese sentiment in Cambodia, fuelled by resentment of Vietnam's expansion over the centuries.

The 1,270-kilometre (787-mile) border has remained essentially unmarked and vague since French colonial times, with stone markers and boundary flags having disappeared, while trees lining it were cut down.