Sam Sokong, a defence lawyer for Kem Sokha, deputy leader of the Cambodia National Rescue Party, said they will appeal the verdict, which followed a trial that lasted only several hours.
“The trial conducted did not comply with procedures,” he said.
Kem Sokha, who was not in court, was convicted of twice ignoring a summons to answer questions related to a case involving his alleged mistress. He refused, saying the legal moves were part of the ruling party’s attempt to cripple the opposition.
Riot police were outside the court, and nearly 1,000 opposition supporters gathered in front of their party headquarters, with riot police watching them from about 500 meters away. There were no reports of violence.
Opposition politician Ou Chanrith said the party was not surprised by the verdict, and urged supporters to continue challenging government suppression.
The case is one of several hanging over opposition leaders in what is generally seen as an attempt to disrupt their organising efforts ahead of local elections next June. The next general election is not until the middle of 2018, but holding power at the local level is an advantage when national polls are held.
Before the verdict, Kem Sokha appeared before his supporters and accused the government of using the courts to stop him from speaking out and prevent him from taking part in the elections.
A statement issued this week by the UN High Commissioner for Human Rights expressed concern “about the escalating atmosphere of intimidation of opposition politicians, their supporters, civil society, and peaceful demonstrators in Cambodia”.
It noted “a host of legal charges” faced by Kem Sokha and 29 other opposition supporters. It said 14 of them had been given heavy prison sentences despite raise serious concerns about the fairness of the proceedings.