United Nations envoys have urged Cambodia to release five human rights workers, detained in the fall out of a sex scandal that engulfed the country's floundering opposition movement.
Four current and one former employee of the Cambodian Human Rights and Development Association (ADHOC) were jailed in April for allegedly encouraging a 25-year-old hairdresser to deny having an affair with acting opposition leader Kem Sokha.
The case was seen as PM Hun Sen's latest effort to hamstring an opposition vying to end the strongman's 31-year domination of Cambodian politics, though the politician was pardoned last month by the king.
On Tuesday two UN rights experts questioned the "legal basis" of the rights workers' detentions, describing them as "arbitrary".
"They have been held hostage long enough, it's time for their release," Rhona Smith, the UN special rapporteur on the situation of human rights in Cambodia, said in a statement.
She alleged that Cambodian authorities have used criminal provisions as "a pretext to suppress and prevent the legitimate exercise of the right to freedom of expression".
Smith's call was also endorsed by human rights expert Sètondji Roland Adjovi, who currently heads the UN Working Group on Arbitrary Detention, the statement said.
Government officials could not be reached immediately for comment.
Rights groups have long accused Hun Sen of using Cambodia's court system to bludgeon critics into silence.
Dozens of opposition figures and rights workers have been jailed over the past year as Hun Sen hardens his stance on criticism ahead of local elections in 2018.