GENEVA (Reuters) - Human rights activists called on China on Wednesday to stop detaining lawyers and critics, voicing concern for their health and fate in custody after the death of jailed Nobel laureate Liu Xiaobo attracted international attention in July.

China said the concerns had no basis in fact.

The activists highlighted the case of Jiang Tianyong, a prominent human rights lawyer disbarred in 2009, who disappeared last November and was held incommunicado for six months.

Jiang’s verdict is pending on charges of subversion, to which he confessed at a trial last month, saying he had been inspired to overthrow China’s political system by workshops he attended overseas.

“The trial can be reasonably called neither fair nor impartial. In just the most obvious violation of due process, Mr Jiang was shown in a televised confession on state media in March 2017,” Sarah Brooks of International Service for Human Rights told the United Nations Human Rights Council.

“Jiang’s physical and psychological health are a subject of great concern, given the real risks of abuse in places of detention,” she said.

A Chinese diplomat told the Council that China firmly objected to the accusations about its legal handling of Jiang’s and other cases, and said the NGOs should respect Chinese law and give up “outrageous tactics”.

“Jiang Tianyong is suspected of provoking trouble illegally, holding state secret documents, inciting subversion of the state and other criminal activities. He pleaded guilty,” the diplomat said.

China’s treatment of dissidents stirred an outcry this year when Liu Xiaobo, serving an 11-year sentence for “citing subversion of state power”, died after being denied permission to leave the country for treatment for late-stage liver cancer.

His wife, Liu Xia, has been under house arrest for six years and her whereabouts and condition since his death are unknown, Brooks said.

“Ms Liu Xia currently has personal freedom,” the Chinese diplomat told the Council, adding that China had picked the most qualified medical experts to treat Liu Xiaobo and given him medical parole.

Brooks also highlighted the case of Ilham Tohti, declared a case of arbitrary detention by a U.N. panel in 2014, who is serving a life sentence for “separatism”.

The Chinese diplomat said Ilham’s crime was clear.

“Ilham’s case has nothing to do with human rights. He was trying to justify the acts of terror, divide the country and incite hatred, which no country could tolerate,” she said.

Zhang Qing, the wife of activist Guo Feixiong, told an NGO event in Geneva on Monday that he has suffered after being sentenced to six years in prison in late 2015. He conducted a 101-day hunger strike in 2016 to protest conditions.

“Guo has encountered a wide range of brutal and evil torture in jail, such as 13 days and nights of sleep deprivation, high-voltage taser to his private parts to extract a confession,” she said.

Guo was a “veteran political prisoner” whose voice had been silenced for demanding reforms, said Zhang, who lives in the United States.

Human Rights Watch said this week that Beijing is waging a campaign of harassment against Chinese activists who seek to testify at the U.N. about repression, which it called the worst since the Tiananmen Square democracy movement was crushed. China’s foreign ministry dismissed the accusations.

U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein, addressing the Geneva forum on Monday, said that China was drafting its first national law on detention centres, with the aim of improving treatment, oversight and accountability.

Zeid urged the government “to ensure that the law grants access to independent legal counsel and family members, as well as addressing the ill-treatment in detention and deaths in custody”.