Blind Chinese dissident Chen Guangcheng is under "US protection" in Beijing after escape from house arrest, a US-based rights group told the BBC.
Earlier, fellow Chinese activist Hu Jia also confirmed Chen was in the US embassy.
Reuters reported neither the US nor China have commented on the claims.
Chen is thought to have escaped under the strict watch of guards and surveillance equipment around his village home in Shandong province.
The BBC wrote the move comes at a particularly sensitive time, ahead of a visit from US Secretary of State Hillary Clinton next week and top White House officials; and could overshadow those talks.
Clinton has repeatedly called for the Chen's release.
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"This is a pivotal moment for US human rights diplomacy,” said Bob Fu, ChinaAid President. "Because of Chen's wide popularity, the Obama Administration must stand firmly with him or risk losing credibility as a defender of freedom and the rule of law. If there is a reason why Chinese dissidents revere the US, it is for a moment like this."
Chen addressed Chinese premier Wen Jiabao in a video posted on YouTube on Friday, detailing "cruel" abuses he said he and his family have suffered during more than 18 months of heavily guarded detention in their home, according to CNN.
Chen, a self taught lawyer, has campaigned against forced abortions and been held under extra-legal confinement since September 2010 when he was released from jail.
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