Chinese police have told relatives of leading human rights lawyer Gao Zhisheng that he disappeared while he was taking a walk in September, rights groups said on Friday, DPA reported.
Gao's brother, Gao Zhiyi, was told by a Beijing police officer who detained the laywer in February that he "got lost and went missing while out on a walk" on September 25, US-based China Aid said in a statement posted on its website.
"This is the first time a Chinese government official has hinted that they no longer have Gao Zhisheng in their custody, leading China Aid to believe Gao's condition has taken a turn for the worse," the group said.
The website of the Hong Kong-based China Human Rights Lawyers Concern Group carried a similar report quoting Gao Zhiyi.
China Aid president Bob Fu said it was "totally unacceptable for the Chinese government to lose track of their own prisoner."
"It is absolutely clear that he was forcibly taken from his home in February 2009," Fu said. "Nearly a year later, the Chinese government now says they do not have him."
Gao's last contact with his brother was a telephone call in early September, when he was only able to say "I'm ok" before the line went dead, China Aid said.
Gao's wife, Geng He, and their two children made a dramatic escape from close police surveillance and arrived in the United States in January 2009 after travelling overland from China to Thailand.
Gao, 44, who was nominated for the 2008 Nobel Peace Prize, was detained by police on February 4.
He is a self-taught lawyer who built a reputation as a stout defender of people who suffered injustices at the hands of Chinese government officials and the police.
Gao was not afraid to take on the most sensitive cases despite threats, violence and imprisonment by the authorities under China's ruling Communist Party.
In recent years, he openly criticized China's one-party rulers and campaigned on behalf of protesting farmers, dissidents, Christians, AIDS activists and fellow rights lawyers.
Gao also came into conflict with police and state security officers through public complaints about their constant surveillance and harassment of him.
An English translation of his book, A China More Just, was published in 2007.
The government closed Gao's Beijing-based Shengzhi law firm in 2005 after he called via the internet for an end to the persecution of members of the Falun Gong meditation movement who were sent to a re-education camp.
It tried to silence him by passing a three-year suspended prison sentence for subversion at a closed trial in December 2006.