The Appeal Court on Wednesday upheld a lower court decision to arrest and jail unionist Rong Chhun over his claims that Cambodia had ceded land to Vietnam, denying him release on bail as his supporters continued to rally outside the court.

Chhun, the president of the Cambodian Confederation of Unions and a representative of the border-focused advocacy group Cambodia Watchdog Council, was arrested on the evening of July 31, then charged with incitement to commit a felony and detained the next day over his statements about border markers between Tbong Khmum province and Vietnam.

Speaking to reporters after the closed-door hearing, defense lawyer Chuong Choungy said Appeal Court Judge Khun Leang Meng rejected Chhun’s bail request and petition against his provisional detention sentence.

Choungy said the judge claimed the imprisonment was to prevent Chhun from committing further offenses and to ensure the accused followed court procedures, which Choungy called a violation of his client’s freedoms.

The attorney also questioned the legality of Chhun’s nighttime arrest.

“[We] lawyers think that authorities violated the law, so that’s why [we] appealed this imprisonment,” he told reporters.

Choungy said his client had posted on social media last month after visiting border markers 114 and 119 in Tbong Khmum, saying that Chhun wanted to know the truth about the area and urge the government to prevent Vietnam from encroaching on Cambodian territory at the border — long an incendiary political issue.

“Authorities based [the charge] on a post on social media and accused him, and he claimed that what he did is for the benefit of society and for [national] territory,” he said. “Rong Chhun said he did not incite to cause chaos.”

But officials have denied Chhun’s claims that Cambodians have lost land at the border to Vietnam, and called his statements “fake news.”

During the hearing, about 50 people, including Chhun’s relatives and youth activists, gathered outside the court, holding pictures of Chhun and other detained activists to demand their release.

Chhun’s arrest has sparked several protests near the Phnom Penh Municipal Court this month, which culminated in the arrests of youth activists, including Hun Vannak and Chhoeun Daravy, as well as Khmer Win Party president Suong Sophorn after he too commented on border issues.

Long Rim, a teacher who joined Wednesday’s protests, echoed statements from Chhun’s lawyer, saying he felt the union leader’s comments were intended to improve society and his imprisonment was unjust.

“I do not think that what he did was a mistake [worth] being charged, being punished and being persecuted,” Rim said. “So I cannot be silent. I have to participate. I have to demand [the court] to drop all charges and let him be free.”

During a speech earlier this month, Prime Minister Hun Sen warned that anyone who continued to criticize the government’s actions at the Vietnam border, and claimed demarcation was resulting in Cambodia losing land to its neighbor, would be arrested.

On Tuesday, the premier tasked the government’s Joint Border Committee to visit Cambodians in Tbong Khmum who claimed to have lost their land to Vietnam due to border demarcation, and potentially hold a seminar to explain border issues to anyone concerned.