PHNOM PENH (Reuters) - Cambodia’s parliament voted to change party laws on Monday to re-distribute seats if a party is dissolved after the government filed a lawsuit earlier this month to dissolve the main opposition party, part of an escalating political crisis.

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Lawyers from the interior ministry filed a lawsuit on Oct. 6 to demand the dissolution of the opposition Cambodia National Rescue Party (CNRP), in a move that would help Prime Minister Hun Sen to extend his 32-year rule when the nation votes in an election next year.

The latest move comes amid growing concern from the United Nations and rights groups over what they say is Cambodia’s deteriorating human rights and political situation ahead of the key election.

It follows an exodus by several opposition figures - nearly half of Cambodia’s opposition parliamentarians fled abroad in September and early October - as Hun Sen moves to tighten his grip on power by silencing critics in the lead-up to the polls.

The attempt to disband the CNRP comes after its leader, Kem Sokha, was charged with treason following his arrest on Sept.3.

The government said the CNRP had conspired with foreign advisors to topple the government, citing a 2013 video clip that shows Kem Sokha talking about a plan to take power with the help of Americans.

Monday’s parliamentary vote on the new amendments was supported by all 67 parliamentarians present from Hun Sen’s ruling Cambodian People’s Party (CPP), while the CNRP boycotted the morning session.

Under the new laws, “if a political party abandons its seats, is delisted, is disbanded or dissolved, a list of candidates or members of parliament of that party are no longer valid and beneficial.”

The laws require that National Election Committee re distribute seats to other parties participating in elections within seven days.

Cheam Yeap, a lawmaker from the ruling CPP party, said the amendments were aimed at “guaranteeing long lasting political stability” in Cambodia.

“Seeing the actions of betraying the nation and people by the CNRP leader Kem Sokha, with the obvious evidence, the signatory lawyers asked for the amendments on these four laws,” Cheam Yeap told the parliament on Monday.

There was no debate on the amendments on Monday and the government has not provided new evidence against Kem Sokha, besides the 2013 video.

Mu Sochua, deputy president of the opposition CNRP, who fled Cambodia earlier this month in fear of arrest, said that parliament’s move was unconstitutional.

“It’s a total violation of the constitution and the will of the people. The highest national institution - the National Assembly will not be legitimate,” Mu Sochua, who has called for targeted sanctions against Cambodia, told Reuters by e-mail.

“Authors and anyone adopting the proposed amendments will take part in putting an end to democracy in Cambodia.”