The announcement from Chinese human rights lawyer Gao Zhisheng that he is to retire from activism have many fearing he is under immense pressure from the authorities to give up his career. Peter Simpson reports from Beijing.

Though most of the mystery surrounding human rights lawyer Gao Zhisheng's disappearance has now been solved with his return to Beijing, doubts about his well-being remain.

Gao says he will give up activism and championing the rights of China's disadvantaged groups.

Joshua Rosenzweig is from the Dui Hua Foundation rights group - which campaigned for Gao's release. He says he is concerned Gao has been forced by Chinese security authorities to choose between his career and his family.

And he says it is still unclear if Gao has been freed or if he is still under police surveillance or even detention.

"It would be easier to accept Gao's choice and his statement if there wasn't still the strong suspicion that those choices are not being made wholly voluntarily and he's been subjected to a great deal of pressure and even coercion," he said.

Gao disappeared in January 2009, when he was taken into police custody. For more than a year, his family and associates had no idea of where he was. This week, he unexpectedly returned to his home in Beijing, where he spoke with journalists.

Looking thinner than before he was charged with subversion and taken away, the often tearful Gao said that he had been through what he described as cruel experiences.

He said he now wants to put the past behind him.

Gao says the main basis for given up activism is for the sake of his family. He adds that being reunited with his loved ones is his instinctive goal.

He says his children need him as they grow up.

Gao says he knows his decision to retire will disappoint many - but he wants what he describes as relative control over his life.

Rosenzweig says international pressure from governments and the foreign media had forced Beijing to let the world know where and how Gao was.

And he says the loss of the lawyer - who spoke up for the poor and oppressed groups such as the Falun Gong spiritual movement - would leave a gaping hole in Chinese activism.

Gao's wife and two children live in the United States. They escaped from China following his arrest.