HANOI (Reuters) - A court in Vietnam upheld a five-year prison sentence on Monday for a dissident convicted of anti-state activities who violated the terms of his probation, state media said, the latest ruling in a series against activists.

Nguyen Van Oai, 36, a prominent human rights activist and blogger who has been publicly critical of the Vietnamese government’s handling of human rights and environmental issues had been sentenced to four years in jail in 2013 for “activities aimed at overthrowing the government”.

He was released in January 2017 after serving his term but arrested days later for violating the terms of his probation and resisting arrest.

The Supreme People’s Court of Vietnam said on its website that Oai had insulted and beaten two security personnel who were monitoring his probation.

He was then sentenced to another five years in jail last September and a further four years on probation.

Following an appeal, Oai’s jail term and probation were both upheld on Monday, the state newspaper Vietnamplus reported.

“The verdict was unfair and not objective,” Oai’s lawyer, Ha Huy Son, told Reuters by telephone.

The People’s Court, which held the trial in the central province of Nghe An, did not respond to a request for comment outside office hours.

Despite sweeping economic reforms and growing openness to social change, communist Vietnam retains tight media censorship and does not tolerate criticism.

In November, a court upheld a 10-year jail sentence for another prominent blogger, Nguyen Ngoc Nhu Quynh, known as “Me Nam”, or Mother Mushroom, who was jailed for publishing propaganda against the state.

Human rights groups have expressed alarm over Vietnam’s biggest crackdown on activists and dissidents for years.

“This is more proof that Vietnam’s ‘appeal’ process is a charade for international consumption, with its kangaroo courts only acting positively when the government indicates the convicted individual has been highly cooperative,” said Phil Robertson, Human Rights Watch deputy director for Asia.