Human Rights Watch has accused the International Olympic Committee of being complicit in China's rights abuses in the lead-up to the 2022 Beijing Winter Games.
It follows the call from IOC President Thomas Bach with Chinese tennis player Peng Shuai, who supporters say may be under political duress.
Foreign governments and rights advocates increased their criticism of China's human rights practices when Peng disappeared for nearly three weeks after alleging on social media that China's former Vice-Premier Zhang Gaoli had sexually assaulted her.
China's foreign ministry has urged "certain people" to stop the "malicious hyping" and "politicisation" of the issue.
But the United Nations Human Rights Office (UN HRO) reiterated calls for Chinese authorities to fully review Peng's allegations with a spokesperson Marta Hurtado saying officials should carry out a 'transparent' investigation.
A former doubles world No.1, Peng appeared over the weekend in Beijing and held a video call with Bach on Sunday.
But the Women's Tennis Association and top current and former tennis players have called for reassurance that Peng is safe, and rights groups have labelled efforts by Chinese state media to allay concerns about her wellbeing as unconvincing.
HRW's China director Sophie Richardson told a news briefing on Tuesday the IOC had shown a "remarkable lack of judgement" in its handling of the Peng case and "active complicity" in Beijing's abuses.
She said its interest seemed to be to keep the Games on track, not the welfare of athletes.
Richardson also criticised Bach for failing to make clear publicly whether he had asked Peng if she had access to a lawyer or wanted to file charges around serious sexual assault claims, and encouraged governments to boycott diplomatically the Beijing Games, set for February.
"The IOC has shown in the last few days just how desperate it is to keep the Games on the rails, no matter the human costs," Richardson said, while also slamming corporate sponsors of the Games for staying silent on Peng.
The IOC did not immediately respond to an email requesting comment.
Amnesty International's China researcher Alkan Akad said the video call did little to ease fears over Peng's wellbeing and the IOC was entering "dangerous waters".
Reuters with EFE
Australian Associated Press