Cambodia's ​former opposition leader Kem Sokha, who was serving a 27-year sentence for treason, has been pardoned, the country's former prime minister said.

Hun Sen, ​who is currently Cambodia's acting head of state, said he signed a decree pardoning Sokha on behalf of King Norodom Sihamoni.

Sokha, the former leader of the now-dissolved Cambodian National Rescue Party (CNRP), was first arrested in 2017 over a video where he said he had received support from US pro-democracy groups.

He has been held under house arrest since he was found guilty of treason in 2023. The charges have been widely derided as politically motivated by human rights groups.

Hun Sen posted on Facebook that Sokha had been "pardoned", alongside a photo of the royal decree signed by him.

The pardon came after an appeal against Sokha's sentence was rejected last month. But it did not include overturning a ban on the politician leaving Cambodia for five years.

Hun Sen, who ruled Cambodia for nearly four decades, has been accused of weaponising the country's courts to target his opponents. He stepped down as prime minister in 2023 and handed power to his eldest son, Hun Manet.

However, Hun Sen still wields immense power in Cambodia and is acting head of state while King Norodom Sihamoni receives medical treatment abroad.

Sokha's CNRP party came close to securing a shock victory in the 2013 general election victory over Hun Sen's Cambodian People's Party (CPP).

The opposition leader was arrested in 2017, less than a year ahead of the next general election, which the CNRP was banned from contesting.