Human Rights Watch on Tuesday accused Beijing of sabotaging United Nations efforts to promote rights and slammed the world body for often capitulating to Chinese pressure.
"China engages with the UN on human rights but often with the goal of aggressively silencing criticism and eroding access for activists who work on China," HRW chief Kenneth Roth said in a statement.
He acknowledged that China was far from the only country misbehaving at the United Nations.
"But its Security Council membership, global influence, and fierce crackdown on civil society at home make it a model of bad faith that challenges the integrity of the UN rights system," he warned.
His comments came as the organisation launched a new report detailing Chinese efforts to harass independent activists, mainly from China, who attempt to participate in UN human rights forums.
Chinese foreign ministry spokesman Geng Shuang rejected the criticism, saying Beijing "attaches high importance and is committed to promoting and protecting human rights."
He urged "relevant organisations (to) remove their tainted lenses and view China's human rights development and contributions to international human rights causes in an unbiased way and stop groundless accusations."
In its report, HRW accused Chinese officials of routinely photographing and filming activists on UN premises, in violation of UN rules, and barring Chinese activists from travelling to the UN Human Rights Council in Geneva.
Beijing has also used its clout to block non-governmental organisations critical of China from receiving UN accreditation and managed to blacklist accredited activists from taking part in UN events.
HRW acknowledged that taken individually, the Chinese actions might not seem so serious.
"But taken together, they amount to what appears to be a systematic attempt to subvert the ability of the UN human rights system to confront abuses in China and beyond," the report said.
In the most shocking case, Chinese authorities detained activist Cao Shunli in 2013 as she attempted to travel to Geneva ahead of a UN review of China's rights record.
She died in custody.
With China scheduled for the next so-called Universal Periodic Review of its human rights record in 2018, the organisation voiced concern that many Chinese activists might opt to stay away.
Cao death "sends a signal to anybody who dares to stand up to Xi Jinping and his government," Roth told AFP.
HRW's report also said the UN often folds to pressure from China, pointing to the example of well-known ethnic Uyghur activist Dolkun Isa who in April was ejected without explanation from the UN headquarters in New York, despite being fully accredited to participate in a forum on indigenous issues.
A few months earlier in January, when Chinese President Xi Jinping visited Geneva, UN officials took the unusual step of sending home many of the 3,000 staff members at the UN European headquarters and barring NGOs from attending his speech.
"Unless the UN and concerned governments put a stop to China's efforts to manipulate or weaken UN human rights mechanisms, the UN's credibility and indeed its ability to defend rights in China and around the globe are at risk," Roth warned.