A Chinese court has secretly convicted and handed down a four-year jail sentence to one of China�s most outspoken human rights lawyers, Yu Wensheng, on the charge of �inciting subversion of state power�, according to his wife.

Yu�s wife, Xu Yan, told the Guardian that she was informed by phone by the prosecutor�s office in Xuzhou city in the eastern province of Jiangsu that her husband�s term was ordered in a closed door sentencing on Wednesday morning. The Xuzhou city intermediate people�s court also deprived Yu of his political rights, meaning he is barred from serving in public positions, publishing and speaking publicly, for three years.

His sentencing comes after his secret trial in May 2019, which took place without the knowledge of his family.

During Yu�s more than two years in detention, he was barred from meeting his family and the lawyers they hired, and there were widespread fears that he was tortured in custody. In April last year, the UN working group on arbitrary detention said Yu should be released.

His wife said Yu was �in a very isolated situation� as none of his relatives, including herself, or lawyers appointed by the family were present at the trial.

�He can�t accept this outcome. He would appeal,� his wife said. �I demand his unconditional release.�

As one of the staunchest government critics in the country, Yu had repeatedly weighed in on politically sensitive issues despite intensifying efforts to stifle dissent under China�s leader Xi Jinping.

Yu, 52, was picked up by police near his home in Beijing on 19 January 2018 as he walked his son to school and later charged with inciting subversion of state power. The day before, he published an online post calling for the removal of Xi and for reforms in the legal and political systems. Three months earlier, Yu also demanded Xi�s resignation in an open letter, accusing China under his rule as �marching backwards�. Yu�s legal licence was revoked shortly before he was taken away.

Yu had long been seen as a thorn in the side of the authorities. He had tried to sue authorities for failing to shield Chinese citizens from pollution and represented activists and dissidents, including Wang Quanzhang, a fellow attorney who vanished into detention in the summer of 2015 and was later sentenced to four-and-a-half-years in jail for subversion. Wang was released in early April this year but was barred from being reunited with his family for weeks.

Yu had also been detained for more than three months in 2014 after voicing his support for pro-democracy protests in Hong Kong and was tortured in detention.

Amnesty International�s Asia-Pacific regional director, Nicholas Bequelin, said Yu�s sentencing is �nothing but political persecution dressed up as legal process�.

�The secret sentencing of yet another human rights lawyer marks a new low for what is left of the rule of law in China,� he said.

US-based rights group Chinese Human Rights Defenders said Yu joined �a long list of Chinese human rights lawyers, activists, dissidents, and journalists� convicted on national security charges for exercising and defending human rights.

�China is in the process of imposing a national security law on Hong Kong to further the suppression of free expression and assembly in the territory,� it said.

The Hong Kong-based Chinese Human Rights Lawyers Concern Group and 17 other international rights groups and individuals issued a joint statement to condemn Yu�s sentencing and urged his immediate release.