Sia Phearum, the former executive director of the Human Rights Task Force, refused to appear as a witness at Phnom Penh Municipal Court on Tuesday for ex-Cambodia National Rescue Party (CNRP) President Kem Sokha’s case, on claims he does not trust the court system.

Phearum was summonsed by Investigating Judge Ky Rithy, to be questioned as a witness. However, he failed to appear and instead criticised the judicial system in the Kingdom for lacking independence and following orders from the government.

“I am not interested in the summons because I think the court is just a puppet which follows the orders of politicians. There is no independence as an institution,” he said via Facebook Messenger from the US, where he now lives.

Asked why he was summonsed in Sokha’s case when he was just an NGO director, Phearum avoided the question and instead said: “An NGO does its work with independence and does not support any political party.”

Phearum is one of eight witnesses Rithy summonsed. In February, Chhim Phalvorun, Cambodia People’s Party (CPP) spokesman and former staffer at the Cambodian Centre for Human Rights, appeared for questioning.

Phnom Penh Municipal Court spokesman Ly Sophana said last week that three witnesses had appeared for questioning, with two appearing last Friday, although he did not name them.

Rithy and Sophana could not be reached for comment on Tuesday.

Sokha was arrested last September at his home in Phnom Penh and charged with “treason” after a video emerged of a speech he gave in Australia in 2013, where he talked about the role of democratic grassroots movements in overthrowing regimes at the ballot box, and the political advice he received from the US.

If he is found guilty, he faces up to 30 years in jail.

Phearum blamed Prime Minister Hun Sen for Sokha’s arrest and claimed the latter feared Sokha’s and ex-CNRP President Sam Rainsy’s popularity, and wanted to clear the way of any challengers.

CPP spokesman Sok Eysan said Phearum did not appear because he is guilty, and that he considered the comparing of popularity totally absurd.

“Hun Sen entered the political arena at a young age to promote peace, but convict Rainsy entered politics not for the nation, but to seek revenge on the monarchy for calling his father a traitor since 1959. So the two personalities have different levels of political wisdom,” he said.

Sam Sary, Rainsy’s father, was a former top government official and ambassador to England in the 1950s who fell out of favour with then-Head of State Prince Norodom Sihanouk and fled Cambodia when his name was linked to an alleged coup plot.