Blind Chinese dissident Chen Guangcheng is under "US protection" in Beijing following a dramatic escape from house arrest, a US-based rights group says.
The group, ChinaAid, also says high-level talks are under way between US and Chinese officials over his fate.
Earlier, fellow activist Hu Jia said Mr Chen was in the US embassy. Neither country has commented on the claims.
Mr Chen's escape could overshadow a visit to Beijing next week by US Secretary of State Hillary Clinton.
She has repeatedly called for the dissident's release.
A statement from the Texas-based ChinaAid group said it had "learned from a source close to the Chen Guangcheng situation that Chen is under US protection" in Beijing.
The group is led by Bob Fu, an American-based human rights campaigner and friend of Mr Chen.
On Friday, Hu Jia - another friend of Mr Chen and himself a prominent activist and dissident - told the BBC he had met Mr Chen in the US embassy in Beijiing in the last 72 hours, after his escape from house arrest in the eastern province of Shandong. He said Mr Chen had scaled a high wall before being driven hundreds of kilometres to Beijing.
Mr Chen escaped on Sunday, activists say, and has since released a video addressed to Prime Minister Wen Jiabao.
There are reports that his brother and nephew, and others who helped him escape, have now been detained by police.
he rights group Human Rights in China quoted a source who knew about Mr Chen, and said his nephew Chen Kegui was taken away from his home by more than 30 police officers.
UN human rights chief Navi Pillay said she was concerned for the well-being of Mr Chen and his family, who live in Dongshigu town, Shandong province.
"I'm disturbed to hear reports that other family members, including his brother Chen Guangfu and nephew Chen Kegui, have now been detained," she said in a statement.
Chen Guangcheng, 40, was placed under house arrest after being released from a four-year jail sentence in 2010. Reports suggest authorities only realised he had escaped on Thursday.
In his video addressed to Prime Minister Wen, delivered from a darkened room, Mr Chen said outwitting his guards had not been easy.
In the appeal, posted online by Boxun, a Chinese dissident news website based in the United States, he asks that:
- Prime Minister Wen investigate and prosecute local officials Mr Chen says beat up his family members
- The safety of his family be ensured
- Corruption in general in China be dealt with and punished according to the law
The Chinese authorities have come under international criticism for their treatment of him. At one point his daughter was barred from school. Many sympathisers who have tried to visit his home say they have been beaten up.
A self-schooled legal activist, Mr Chen is known for revealing rights abuses under China's one-child policy and has accused officials in Shandong province of forcing 7,000 women into abortions or sterilisations.
He Peirong, another China-based activist who had also campaigned for Chen Guangcheng, has also been detained at her home in Nanjing, according to other activists.
The Chen affair comes at an unwelcome time for China's leaders, who have been embroiled in a lurid political scandal involving disgraced former party boss Bo Xilai.