The blind Chinese rights activist, Chen Guangcheng has made a daring escape from his captors and put out a video exposing the abuse and beatings that his family suffered under house arrest.

Evading almost 90 guards who have surrounded his village home for more than a year, Chen is said to have found refuge in a "safe" location in Beijing.

His revelations about the illegal detention – which included savage beatings that left family members with broken bones and harrassment of his children – throw a harsh light on a Chinese government that is already reeling from a corruption and wire-tapping scandal sparked by the death of British businessman Neil Heywood.

Looking gaunt, Chen blamed his treatment on local officials and the Chinese state's obsession with maintaining stability at all costs. He said his greatest concern was that the authorities would carry out "insane retribution" on his family, several of whom have already been placed under arrest.

Human rights campaigners expressed delight that Chen – whose protracted, illegal detention has drawn international attention – is no longer in the hands of the authorities, but there are concerns about revenge attacks on his wife, children, brother and human rights activists who helped him gain liberty.

"I have confirmed that Chen is now in Beijing. I would say the fact that he successfully escaped is a miracle," said Hu Jia, a prominent rights activist. "It's like a real Chinese version of The Shawshank Redemption. I heard he got through eight security checks."

In a video message, Chen confirmed he was beaten and said 90 to 100 local officials were involved in his detention. He expressed "extreme concern" about retaliation against his family. Chen confirmed reports about his maltreatment that have appeared over the years. "The truth was even worse," he said. "I formally made three requests to Premier Wen Jiabao. First, severely punish criminals. Second, look into this yourself, and third, send a special investigation team to find out the truth."

Chen is believed to have used the cover of darkness in which his blindness – he lost his sight at the age of five – gave him an advantage over his captors. He previously attempted to dig a tunnel without success.

It is not yet clear how Chen evaded the officials, police and plainclothes thugs who have been permanently camped in and around his home in Linyi since his release from prison in 2010. But activists said it was not an individual, opportunistic bid for freedom.

"This wasn't a sudden thing. In order to escape from a place with so many guards must have taken a great deal of planning," said Phelim Kine of Human Rights Watch.

Chen's exact whereabouts are unknown. Several sources said he was in a place that was safe from the scrutiny of security agencies, prompting speculation that he may have taken refuge in a foreign embassy or consulate. The US embassy has declined to comment on the case.

According to the US-based group China Aid, Chen was "100% safe" in Beijing. But the group said that the activist He Peirong, one of the people who helped Chen flee, was arrested at her home in Nanjing on Friday morning.

He, who is said to have been in close contact with the Chen family, had earlier told CNN that Chen's hands were trembling, but his spirits were high. She said he was injured in the escape.

If Chen is caught, he faces the risk of severe extra-legal punishment from his guards. Several people close to Chen have already been rounded up, prompting fears of retribution.

According to Human Rights in China, Chen's brother Chen Guangfu was taken away from Dongshigu village on Thursday evening. His nephew, Chen Kegui, is also in hiding after a bloody battle with a kitchen knife when he tried to defend his mother from intruders led by the village chief.

Local public security bureaus were not picking up their phones.

"The wife [Yuan Weijing], children and mother are on the extreme edge of vulnerability. They have already been brutally victimised for merely trying to get outside the compound for food or medical attention, so it is quite likely that the plainclothes thugs will react quite brutally to his escape. It is our hope that all diplomatic missions will make strong representations for their safety," said Kine.

Chen has suffered the wrath of Shandong officials since 2005, when he exposed a programme of forced abortions to reach targets linked to China's one-child policy. Although he was released from a four-year jail term in September 2010, he and his family have continued to suffer detention and beatings.

Until his safety and liberty are confirmed, associates say they fear for his health, which deteriorated during his detention.

"I don't know if he is safe now and I am worried about him," said the lawyer Teng Biao. "Chen was not given freedom after being released from prison and he was sick and did not have a chance to see a proper doctor. I am worried about him."