A Cambodian court Friday issued an arrest warrant for opposition leader Sam Rainsy over an old, unserved defamation sentence amid a surge of political tension between him and strongman premier Hun Sen.
The order comes a day after Hun Sen threatened Rainsy with legal action for calling on the international community to pressure him to move towards a peaceful exit from office, which he has held for more than three decades.
The opposition leader, currently touring South Korea, made the comments during his visit to Japan earlier this week, drawing on the historic vote of nearby Myanmar which was ruled for nearly half a century by a military junta.
Taking encouragement from Sunday's historic vote in Myanmar he said it was time to ensure his country achieved full democratisation.
On Friday Phnom Penh Municipal Court ordered police "to arrest and bring the convict Sam Rainsy to serve the (two-year defamation) sentence in jail", according to a copy of the warrant seen by AFP.
Rainsy was sentenced for defamation in the 2011 case while in self-exile outside Cambodia for accusing the country's foreign minister of being a former Khmer Rouge member.
It was one of a string of convictions against the opposition leader, the main challenge to Hun Sen's powerful grip over the country.
Rainsy has always claimed the convictions were politically motivated and only returned to Cambodia ahead of 2013 elections after a royal pardon for criminal convictions.
On Friday Eng Chhay Eang, a senior official from Rainsy's opposition Cambodia National Rescue Party (CNRP), renewed those claims over the latest warrant.
"It is clearly a politically-motivated issue," he told AFP, adding he believed Rainsy was protected from arrest by "parliamentary immunity".
It was not immediately clear if Rainsy had already been pardoned over this latest case.
Up to two million people died of overwork, starvation or execution under the Khmer Rouge during its 1975-1979 rule.
Hun Sen himself was a mid-ranking cadre before he turned against the brutal regime.
In Tokyo on Tuesday Rainsy called on the international community to pressure Hun Sen for a peaceful transfer of power in Cambodia's next elections in 2018.
Rainsy has accused Hun Sen's ruling Cambodia People's Party (CPP) of widespread vote-rigging in the last election.
His party boycotted parliament for a year in protest and only returned in August 2014 on the promise of electoral reform.
But in recent weeks political tensions have reignited with three military members charged over the savage beating of two Cambodia opposition MPs last month.
They were attacked during a demonstration by thousands of CPP backers calling for a key opposition figure to step down as vice chief of parliament. He was later voted out of the role by ruling party MPs.
Hun Sen, 63, has signalled he has no intention of ending his dominance of Cambodian politics -- previously vowing to stay in power until he is 74.
He is frequently accused by rights groups of stifling the opposition through court cases and hard power.
Lashing out after Rainsy's comments in Japan, Hun Sen Thursday chastised the opposition leader for making "groundless accusations" against him for not honouring elections.
"Don't blame (me) if the law takes action against you," he said in a video posted on his Facebook page.