Kim Sok refused to stand as the verdict was read and denounced the court, prompting the trial judge to order guards to force him to his feet.
In addition to serving his prison term, Kim Sok must pay 800 million riels (U.S. $200,000) to Hun Sen and 8 million riels (U.S. $2,000) to the state, sums that his brother said his family will be unable to pay.
"After hearing the news of Kim Sok's conviction, my mother was shocked," Kim Sok's brother Kim Seng told RFA's Khmer Service on Thursday.
"She said she has nothing she can use to help pay her son's fines, since she only possesses a small parcel of rice paddy land.? And Kim Sok himself has no assets that he can use to pay the compensation. He has only two iPhones and an iPad," he said.
Cambodian society at present is not ruled by law, but by the wishes of Hun Sen, Kim Seng said, adding, "My brother's reaction during his trial shows that he is not afraid of the pressures being used against him.? I really admire his bravery!"
Prosecuting attorney Ky Tech meanwhile applauded the court's verdict, calling it fair in view of Kim Sok's open defiance of the court and his sentence.
Kim Sok's lawyer Choung Choungy could not immediately be reached for comment.
Accusations of involvement
Kim Sok was jailed on Feb. 17 after Hun Sen accused him of implying that his ruling Cambodian People's Party (CPP) had orchestrated the July 2016 murder of popular political pundit Kem Ley, though Kim Sok said that he had only been repeating what many Cambodians believe.
Kem Ley was shot dead in broad daylight on July 10, 2016, when he stopped in a convenience store beside a gas station in Phnom Penh.
Though authorities charged a former soldier with the murder, many in Cambodia don't believe the government's story that Kem Ley was killed by the man over a debt.
Just days before he was gunned down, Kem Ley had discussed on an RFA Khmer Service call-in show a report by London-based Global Witness detailing the extent of the wealth of the family of Hun Sen, who has ruled Cambodia for 31 years.
Rights groups accuse Cambodia's judiciary of lacking independence and say the government seeks to limit freedom of expression by using the courts to level defamation charges at reporters and critics of the ruling party.
Reported by Samnang Rann and Vuthy Huot for RFA's Khmer Service. Translated by Sovannarith Keo. Written in English by Richard Finney.
Copyright 1998-2014, RFA. Published with the permission of Radio Free Asia, 2025 M St. NW, Suite 300, Washington DC 20036