HANOI — A court in northern Vietnam sentenced a student activist on Wednesday to six years in prison for using social media to promote a multiparty system and press freedom amid a heightened crackdown on dissent.

Phan Kim Khanh, 24, was also given four years of probation after being convicted of spreading propaganda against the state at the trial, in Thai Nguyen province, his lawyer Ha Huy Son said. ‘‘The evidence was groundless and I think the sentencing is absurd,’’ Son said.

Son said the court convicted Khanh of opposing the communist state by using his two blogs and a YouTube channel to promote multiparty democracy and press freedom.

Khanh admitted in court to having run the social media platforms, but said his main purpose was to fight corruption and he did not know that constituted a crime, Son said.

Khanh was arrested in March while in his final year at the Thai Nguyen University.

Human rights groups have appealed for his immediate release and called on leaders of the Asia Pacific Economic Cooperation meeting in Vietnam next month, including President Trump, to pressure Hanoi to improve its rights record.

associated press