PHNOM PENH - A Cambodian court convened Thursday for the treason trial of more than 100 opposition figures and then deferred proceedings until next year, delaying a case widely condemned as a move by long-serving premier Hun Sen to decimate his political rivals.

A total of 121 defendants, all tied to the dissolved Cambodia National Rescue Party (CNRP), had been summoned to appear Thursday, but just 34 showed up, with many in exile, convinced they would not get a fair hearing.

Deputy prosecutor and court spokesperson Kuch Kimlong confirmed that judges had decided the case be divided into two and heard in January and March.

"Maybe it's related to the issue that the accused need to have defense lawyers," he told Reuters when asked the reason.

Defendants and court staff were seen arriving amid tight security at the Phnom Penh court, with most media unable to enter what police said was a packed courtroom.

The CNRP was banned and its leader Kem Sokha arrested ahead of an election in 2018, allowing Hun Sen's Cambodian People's Party to win every parliamentary seat.

Kem Sokha's treason charges stem from accusations he conspired with the United States to overthrow Hun Sen, which both he and Washington reject.

The opposition crackdown has strained Cambodia's ties with the West and prompted the European Union, its key export destination, to rescind some trade privileges.

Experts say that has only pushed Cambodia deeper into the orbit of China.

Several defendants had complained they had not seen their indictments ahead of what government critics and a United Nations human rights expert have called a politically motivated trial. The government has insisted serious crimes were committed and due process would be followed.

Other defendants believe their inclusion was punishment for supporting the failed return from exile of Sam Rainsy, Hun Sen's biggest rival during his 35-year rule.

Those include Seng Theary, an American-Cambodian lawyer who was among the few to appear on Thursday at what she called "a kangaroo court employing laws of the jungle."