Phnom Penh, Cambodia - A court has begun its "treason" trial for opposition leader Kem Sokha more than two years after his arrest.

Almost no journalists and no non-governmental organisations were allowed into the courtroom on Wednesday, drawing criticism from civil society groups and the press.

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Court officials said the courtroom was too small to accommodate all, and seats were reserved for embassy officials, relatives, and members of Kem Sokha's Cambodia National Rescue Party (CNRP).

Two journalists - one from Voice of America and one from Reuters News Agency - were given unused seats reserved for United States embassy officials and attended the morning session, but were prevented from re-entering in the afternoon.

Kem Sokha's lawyer Pheng Heng told reporters that proceedings were slow to start, and nothing substantive about the charges was discussed.

Pheng Heng said he and his legal team requested to use the full version of the speech - around which the charges against Kem Sokha centre - instead of an abbreviated, two-minute version the courts had so far shown.

The court then showed one hour of the speech but said in order for it to be admitted as new evidence, defence lawyers would have to make a written request.

Kem Sokha was arrested in a midnight raid in September 2017 after a public speech he gave in 2013. In the speech, he talked about receiving support from the US to create change in the country from a grassroots level.

He was released in November last year but barred from leaving the country and engaging in politics.

The charges against Kem Sokha led to the dissolution of his CNRP in November 2017 ahead of national elections in July 2018. The ruling Cambodian People's Party took all 125 seats.

The government's lawyer, Ky Tech, said other than the US, others allegedly involved in the case included Indonesia, Serbia, Australia, Canada, the European Union, Taiwan and India.

'Conspiracy'

Government lawyers started questioning Kem Sokha, Ky Tech said, though he declined to give details. "This could affect the rights of the accused," he told reporters.

In a Facebook statement, Kem Sokha reiterated his innocence.

"I categorically deny the charge of 'conspiracy with foreign powers' which was brought against me," he said. "I did not commit anything of which I am accused."

But government lawyers insisted the case against Kem Sokha was strong. "It's common that a defendant claims that they are innocent. But we ... have an abundance of evidence to prove to the judges."

Kem Monovithya, Kem Sokha's daughter and a CNRP official, called the trial "a farce".

"Kem Sokha is innocent and needs to be acquitted. His political rights also need to be reinstated so Cambodia can get back on the track. Let's move on," she told Al Jazeera.

Her colleague Mu Sochua, CNRP's vice president, agreed. She said fair trial standards were violated by not opening the hearing to the public. "All charges must be dropped," she said.

'What evidence'?

Police guarded roads surrounding the court, while a growing number of activists waited in front of the building to express their support for the opposition leader.

Among them was Sok Yoeung, 74, who said she supported the opposition for about 20 years. "I want to see what evidence they show ... I haven't seen any act by him that shows he betrayed the nation."

Another supporter, Neth Noeun, said she had seen first-hand that the Cambodian courts were not independent. She said her daughter was arrested after someone planted drugs in her bag allegedly because she and her daughter were CNRP supporters. She received a three-year sentence at the time.

"Now it's been more than three years and she is still in prison. They keep changing the date of release. I have not been informed why," Neth Noeun said. "This court is made only for the rich, and the court is not independent."

It has not been announced when a verdict is expected, though news reports suggested the hearings would last three months.

The trial comes at a politically sensitive time with the European Commission scheduled to issue its decision on a preferential trade agreement in February.

The EU has threatened to withdraw the agreement based on human rights concerns. It initiated its formal withdrawal procedure in February last year. Should it decide to pull out, tariffs on Cambodian goods could be reintroduced by mid-year.

The government wants to put on a show for the international community, Naly Pilorge, director of the human rights organisation Licadho, said.

"For this trial to take place now and for the trial to take up to three months, it's clear that it's a show to the international community, in particular to the European Union, in response to the trade preference [agreement ]," she told Al Jazeera.

"[But] if this is a show for the international community, then the court and the government must hold this trial with more transparency than usual. It's one of the most high-profile cases of the past two decades, and the people that voted for CNRP in 2017 are very interested in seeing how the court will proceed with the charges against Mr Kem Sokha."