Human rights lawyer whose year-long disappearance drew international attention says he is now living in Shanxi province

For more than a year, since the Chinese human rights lawyer was taken from his hometown, friends and family have waited anxiously for news of Gao Zhisheng.

But now the outspoken activist, feared by some to be dead, appears to have re-emerged in circumstances as mysterious as his disappearance. Reporters and friends said he spoke to them by phone today, saying he was living at a Buddhist landmark in Shanxi province.

Gao's disappearance in February last year caused international concern, particularly after the release of a graphic account of torture he said he had suffered at the hands of security officials.

Gao told Reuters he had been released about six months ago and was at Wutai mountain, beloved of Buddhist pilgrims because of its many shrines. The 44-year-old said he wanted "a quiet life" and to rejoin his family.

But friends and human rights groups said they remained deeply concerned about his situation, since he seemed to be under surveillance and unable to speak freely.

Although other dissidents have been detained for days or weeks without access to lawyers, it is rare for people to simply vanish for such a long period in China.

Phelim Kine, Asia researcher at Human Rights Watch, said: "In terms of high-profile dissidents and activists, we haven't seen a case as serious as Gao's. It is the most egregious in terms of the length of time, concerns about his safety due to [previous] torture and the obstinacy of the Chinese government in refusing to provide any details."

While there were concerns that someone might have impersonated Gao today, Reuters said he was able to answer questions about previous conversations with the reporter and the venue of meetings they had held.

Teng Biao, another lawyer, said on Twitter he was also convinced it was Gao, pointing out that the man he spoke to not only sounded the same, but made references to Teng's daughter.

Teng said Gao had also confirmed that he had at one stage been in Urumqi, Xinjiang, at the Ye Ma International Business Clubhouse. Earlier this year, a rare official reference to his whereabouts described him as "working in Urumqi".

Human rights lawyer Li Heping, who also knows Gao well, said: "It's certainly him … I could tell from the way he spoke and the way he spoke to me."

But Li added: "I believe he does not have freedom. He sounded like he wanted to hang up. He told me that he had friends around him. I'm sure people around him are limiting what he can say."

"Secondly, he would not tell me exactly where he is when I suggested visiting him … We are very concerned."

Gao told Associated Press he was "free at present", adding: "I just want to be in peace and quiet for a while, and be reunited with my family.

"Most people belong with family, I have not been with mine for a long time. This is a mistake and I want to correct this mistake." Gao declined to answer further questions, saying he was not willing or legally permitted to accept media interviews. Asked if he planned to join his family – now living in exile in the US – Gao told Reuters: "It's not that easy."

The lawyer was at one stage feted by the authorities. The ministry of justice selected him as one of the top 10 lawyers in the country in 2001.

But he angered officials by taking on sensitive cases such as those involving the banned spiritual movement Falun Gong and through increasingly open confrontations. In 2005 he resigned from the Communist party and wrote an open letter to leaders urging them to end the persecution of Falun Gong practitioners.

In 2006 he was given a suspended three-year sentence for subverting the state. His family were placed under constant surveillance at their home and on several occasions Gao was detained again and held elsewhere.

His wife, Geng He, and their two children fled into exile in January last year. Geng said her husband had no idea they were leaving. Shortly afterwards Gao was detained in his hometown in Shaanxi province, prompting human rights campaigners to say they were "intensely fearful" for him.

Days later, Human Rights in China issued the lawyer's account of his seven-week detention in 2007, in which he described brutal and sustained torture. He wrote that security officers beat him all over his body, used electric batons to shock his genitals and warned him he would die if he told anyone what had happened.

News that Gao was contactable appears to have first surfaced on Twitter today, with users posting messages saying relatives had spoken to him and including a phone number.

The phone said to belong to Gao was switched off when the Guardian called.

"If these reports are accurate and Gao Zhisheng is alive and well, we are extremely relieved," added Kine, of Human Rights Watch.

"But the fact is that the whereabouts and fate of Gao have been shrouded in mystery by the Chinese government for far too long. He disappeared into a legal black hole in early 2009 and has not been seen since.

"Until the government allows free and unfettered access to him by legal counsel, family and representatives of the media we remain in the dark."

Whereabouts unknown

4 February 2009 Gao Zhisheng taken from home overnight by security officers, according to human rights groups. They issue statement saying they are "intensely fearful" for his safety.

September Lawyer Teng Biao says via Twitter that Gao made brief call to relatives in July, saying he was OK. Police reportedly tell Gao's brother lawyer has "lost his way and gone missing".

October Duihua Foundation says Chinese embassy in Washington has told it that Gao was allowed to return to his home town in Shaanxi province to pay respects to his ancestors in June, that he was not being mistreated and was not being subjected to coercive legal measures.

January 2010 Foreign ministry spokesman Ma Zhaoxu tells reporters that Gao is "according to Chinese law, where he should be". Days later, when pressed again, Ma says he "guesses" Gao is where he should be.

February Duihua Foundation says Chinese embassy has told it the lawyer is "working in Urumqi" – in far west of the country – and has been in touch with his family. His wife tells Duihua she has not heard from him.

March Gao's brother tells BBC he has spoken to lawyer by telephone, adding: "He said he's quite well … We were worried about whether his life was under threat. Now we are a bit relieved but we can still do nothing."

Reporters repeatedly press foreign ministry spokesman Qin Gang for information on the case. He replies: "I will not answer you...so I hope you will give up such efforts."