PHNOM PENH, Cambodia (AP) — A leading Cambodian opposition politician who was sentenced last month to 18 months in prison on charges of issuing worthless checks was convicted and sentenced on Wednesday to three more years of imprisonment for alleged incitement to commit a felony and incitement to discriminate on the basis of race, religion or nationality.

Presiding Judge Chhun Davy of the Phnom Penh Municipal Court also ordered Thach Setha, a vice president of the opposition Candlelight Party, to pay a 4 million riel ($1,000) fine.

Opposition parties in Cambodia frequently face legal challenges initiated by the government.

The case against Thach Setha was based on remarks posted on social media that he made in January to Cambodian overseas workers about then-Prime Minister Hun Sen and Cambodia’s relations with neighboring Vietnam.

Many Cambodians retain historical suspicions that bigger neighbor Vietnam is intent on annexing their territory, and prejudice against ethnic Vietnamese is common. Critics have targeted Hun Sen because of his close links to Vietnam after he became prime minister in 1985 in a government that was installed by Vietnam, whose forces had ousted Cambodia’s brutal Khmer Rouge regime in 1979.

Some opposition politicians have used inflammatory anti-Vietnamese rhetoric to try to win support, but the government also prosecutes politicians such as Thach Setha who are merely critical of official policy toward Vietnam.

“It is outrageous and unacceptable that Thach Setha has been imprisoned for three years for simply expressing his views via a social media post,” Phil Robertson, deputy Asia director of Human Rights Watch, said in an emailed statement.

He said the government’s repression of the Candlelight Party under current Prime Minister Hun Manet, who succeeded his father Hun Sen in August, means “no one should be fooled that his government will be any better than what we saw under his father’s oppressive rule.”

Thach Setha’s lawyer, Sam Sokong, said his client would appeal the verdict.

The same Phnom Penh court on Sept. 21 sentenced Thach Setha to 18 months in prison for allegedly issuing worthless checks in a case his party called politically motivated.