He said he was disappointed with the agreement, which was hastily reached to provide necessary safety assurances for Chen and his family on the eve of high-level bilateral talks and was initially seen as a victory for both sides to avoid an escalation of the stand-off.

'I feel there are no safeguards for my citizen's rights nor my safety,' Chen said. 'Now I just want to get medical treatment and rest, I haven't thought of other things.'

Chen only found out after he left the embassy from his wife that she had been badly treated by local officials since his escape.

Chen told The Daily Beast, an American news website, yesterday that: 'My fervent hope is it will be possible for me and my family to leave for the US on [US Secretary of State] Hillary [Rodham] Clinton's plane.'

The Foreign Ministry declined to comment on Chen's request to leave with his family and repeated its criticism of the 'unacceptable' way the US had handled the issue.

In Beijing, US State Department spokeswoman Victoria Nuland said US officials had spoken twice yesterday to Chen and also with his wife and 'they as a family have had a change of heart about whether they want to stay in China'. 'We need to consult with them further to get a better sense of what they want to do and consider their options,' Nuland said.

Accompanied by senior US diplomats, including ambassador Gary Locke, Chen, a 40-year-old activist, left the embassy on Wednesday afternoon to go to a Beijing hospital for injuries suffered when he escaped house arrest in his hometown in Shandong , and for a reunion with his wife and two children.

But later he said he was forced to accept the deal because of inadequate information and he changed his mind after speaking to his wife, who was threatened by local authorities after his escape, and friends.

'The Chinese side said I'm free and I'm a lawful citizen, I abided by the agreement and walked out of the embassy. I have so many friends, but I can't see them. My family situation is terrible, my mobile [phone] is disrupted,' he said. 'These things shouldn't happen, and [yet] they happened on the first night straight after the agreement was reached.' He also complained US officials were barred from seeing him in hospital.

Chen said that what his wife, Yuan Weijing, had told him about what happened to his family when he fled into the US embassy was unacceptable, especially after Beijing had promised to improve the situation.

'They said they'll improve [our conditions] and will investigate the situation in Shandong, so I believed them,' he said referring to the information from the Chinese side relayed to him by US officials.

'They installed seven video cameras and, after finding out that I escaped, they barged into my home with clubs and threatened to beat Yuan Weijing to death,' he said. 'Also, they're in my house, in the yard, and on the roof ... this is all unbearable.'

Yuan said: 'I feel we're not safe; of course, we're afraid.'

US officials appeared to have been caught off guard by Chen's sudden change of mind and scrambled to set the record straight and to deflect criticism about its pursuit of a stronger partnership with the authoritarian government in Beijing.

Locke told a news conference yesterday that he could say 'unequivocally' that Chen was never put under pressure to leave. 'We asked him was he ready to leave. He jumped up very excited and said 'let's go' in front of many, many witnesses,' Locke said.

Clinton, who co-chaired the opening of annual bilateral talks in Beijing yesterday, urged China to protect human rights, but did not mention Chen. She spoke to Chen by phone when he was on his way to the hospital on Wednesday. 'Of course, as part of our dialogue, the United States raises the importance of human rights and fundamental freedoms,' she said.

'We believe all governments have to answer our citizens' aspirations for dignity and the rule of law and that no nation can or should deny those rights.'

Analysts said the latest twist in the Chen case was a test for Sino-US ties, leaving both countries with a delicate situation ahead of the US presidential election and the leadership transition in China.