Cambodian opposition leader Kem Sokha was arrested early Sunday and accused of treason, the latest in a flurry of prosecutions brought against critics and rivals of strongman premier Hun Sen.
His surprise overnight detention raises the stakes as Hun Sen's political opponents, NGOs (non-governmental organisations) and the critical press are smothered by court cases and threats ahead of a crunch general election next year.
Hun Sen, 65, is determined to extend his three-decade rule and dismantle the burgeoning popularity of the main opposition CNRP (Cambodia National Rescue Party), who have gained from public anger over inequality and corruption.
In a statement, Hun Sen's government alleged "a secret plan of conspiracy between Kem Sokha, his group, and foreigners that harms Cambodia".
"The above secret conspiracy is an act of treason," the statement said, adding Kem Sokha faced up to 30 years in jail if convicted.
Kem Sokha is the leader of the CNRP which has been battered by court cases, bans and threats against its key figures, including his predecessor Sam Rainsy who fled to France to avoid charges.
In a Twitter post, Kem Sokha's daughter Kem Monovithya said her father was handcuffed and "taken away by 100-200 police without warrant after they raided his home".
The CNRP called the arrest "politically motivated" and illegal because Kem Sokha, a serving MP, is protected by parliamentary immunity.
The arrest came just hours after pro-government website Fresh News ran a report accusing Kem Sokha of discussing the overthrow of Hun Sen with support from the United States.
Fresh News frequently runs leaks from inside the government that often precede an investigation or arrest.
However Saturday's report was based on a 2013 speech Kem Sokha gave to supporters in Australia with cameras present in which he talked about travelling overseas, including to the US to discuss his opposition work.
During the speech he boasted that the US was "advising me about strategies to change the dictatorship in Cambodia".
A former Khmer Rouge officer who defected, Hun Sen has become one of the world's longest-serving leaders through years of wily political manoeuvring and little tolerance of dissent.
He portrays himself as the only person who can bring stability and prosperity to a country once ravaged by civil war and genocide.
In the last decade, Cambodia has become one of Asia's fastest growing economies.
But there is rising anger, especially among the youth, over how that wealth is spread and the cronyism that remains endemic under his rule.
In 2013, the opposition parties made surprise gains, dealing Hun Sen his first ever electoral scare.
Ahead of next summer's national polls, the Cambodian strongman has become increasingly alarmist in his speeches, warning of foreign-sponsored "colour revolutions" and the spectre of civil war if he is voted out of office.
In recent years he has become increasingly hostile towards the United States.
Washington has a complex and fraught history with Cambodia, secretly bombing it during the Vietnam War era and then becoming one the country's biggest aid donors as it tried to rebuild from the murderous Khmer Rouge years.
Last week the US expressed "deep concern" over the state of Cambodia's democracy after the government there ordered out an American NGO and pursued a crackdown on independent media.
Among the media in the firing line is the well respected Cambodia Daily, which often criticises the government.
It faces closure on Monday if it fails to pay a $6.3 million tax bill, a threat it says is a political move to muzzle its critical reporting.
It says the hefty bill was invented by the government and not based on an audit of its books. – AFP