Former opposition leader Sam Rainsy was found guilty of defamation and ordered to pay 4 billion riel (about $1 million) to Prime Minister Hun Sen on Friday for alleging that the premier bribed pro-government activist Thy Sovantha to attack the opposition.

The accusation stemmed from messages leaked from Sovantha’s Facebook account between her and Hun Sen in November. The messages dealt with undermining the now-dissolved Cambodia National Rescue Party, with the prime minister calling Sovantha “grandchild” and offering her $1 million.

Sovantha claimed her page was hacked and the messages fabricated.

During Friday’s hearing, the court played a 26-minute video from January of Rainsy speaking to Cambodian supporters in France.

“Hun Sen bribes Thy Sovantha $1 million . . . He bribed her to do bad things, to attack and cause trouble to the CNRP, to hold protests,” Rainsy said in the clip.

Hun Sen was represented by Ky Tech, the same lawyer who represented the government last month in its case seeking the dissolution of the CNRP.

“What Sam Rainsy said was not true and it affects the reputation of Samdech Techo Hun Sen, the prime minister of Cambodia,” Tech said.

Rainsy, who lives in self-exile in France to avoid a slew of similar convictions widely seen as politically motivated, was found guilty in absentia. His lawyer, Sam Sokong, challenged the validity of the verdict, in part because Sovantha was not present in the courtroom to testify.

“The prime minister is a public figure, and in a democratic society he should not mind criticism . . . The court should have the written statement of Thy Sovantha denying that, or summons her to testify here,” he said.

Yoeurng Sotheara, legal expert at election watchdog Comfrel, said the latest conviction was “the same as the cases before” and “politically motivated”.

“In a democracy with freedom expression . . . the right to express criticism to public figures is granted in the Constitution,” Sotheara said.

“Not everything is defamation,” he added.

Rainsy said in an email on Friday that he is “confident” the more than 400 leaked messages are legitimate, and could be proven so.

“If someone had wanted to invent something to discredit the concerned two persons, they would not have needed to fabricate so many fake messages,” Rainsy said via email on Friday.

“Moreover, nobody apart from the two would have known so many details about their relationship . . . They have never been convincingly denied by Hun Sen.”

Mu Sochua, the former opposition deputy president who fled the country in October, said the conviction against Rainsy would be another black eye on the justice system.

“These series of political cases will continue to make Cambodia a country known for its mockery of justice,” she said by email. “Mr. Hun Sen has nothing to prove but his zero tolerance of true justice.”

Updated: Monday 1 January 2017, 6:52am