Kem Sokha, who was convicted of trying to topple the former long-ruling leader’s government and sentenced to 27 years, “is pardoned”, Hun Sen posted on social media alongside a royal decree signed by him.

Hun Sen, who is president of the Senate and the father of the current prime minister, remains an influential figure in national politics.

Kem Sokha, 72, was arrested on treason charges in 2017 and sentenced six years later but was ordered to serve his time under house arrest in the capital Phnom Penh.

The co-founder of the dissolved opposition Cambodia National Rescue Party, Kem Sokha, has repeatedly denied the charge.

Rights advocates say his prosecution was designed to bar him and his popular opposition movement from politics after the party made electoral gains against Hun Sen’s entrenched Cambodian People’s Party.

UN rights chief Volker Turk said this month he was “deeply concerned” by a Cambodian court rejecting Kem Sokha’s appeal against his treason sentence on April 30.

Monday’s pardon did not undo an additional sentence against Kem Sokha, added by the appeals court, banning him from leaving the country for five years, the royal decree said.

The opposition leader said in a letter to the appeals court dated Monday that he would not appeal against its decision to the Supreme Court, although he was “not satisfied”.

“Resolving this issue with a conciliatory spirit through dialogue between Khmer and Khmer is the best option for the national and Cambodian people’s interest,” Kem Sokha said.