Blind legal activist Chen Guangcheng will escape Chinese persecution if he leaves for the United States, but will find life tough, and may struggle to make an impact abroad, current exiles said.

Beijing has indicated it will allow Chen to leave the country to study in the United States, under a tentative deal with Washington announced during a high-profile visit by US Secretary of State Hillary Clinton last week.

But it remains unclear when Chen, who is receiving treatment at a Beijing hospital for a broken foot injury sustained during his dramatic flight from house arrest, might leave China, or whether he would be able to return.

If he remains in the United States, he faces a new set of challenges abroad, say exiles who have made that difficult transition before.

Wuer Kaixi, a leading figure in the 1989 Tiananmen Square democracy protests who went on the run and slipped out of the country that year, said exile entails a difficult psychological adjustment to a strange new world.

"To live in exile is not easy," said Wuer.

"It is especially tough mentally because you have to overcome a lot of difficulties. The hardest part for me has been the mental anguish I've suffered from being expelled from my homeland."

Chen, a self-taught lawyer, is best known for exposing abuses of China's population-controlling "one-child policy" including forced abortions and sterilisations.

His activism got him thrown in jail for more than four years and, after his 2010 release, he spent nearly two years under what he calls "illegal" house arrest at his home in Shandong province in eastern China.

Despite being blind, Chen, 40, escaped from his home on April 22 and fled to Beijing, where he spent six days holed up in the US embassy before leaving last Wednesday.

Initially, Chen said he wanted to remain in China. But after seeking advice from friends and hearing from his wife of the beatings she sustained at the hands of security agents after his flight, he changed his mind.

Jerome Cohen, a New York University professor who is a friend and adviser to Chen and helped secure him a place at the university, said life in the United States would not be easy.

"He'll be besieged by people wanting him to give lectures. He's going to have people after him to do TV broadcasts, write a book. He's going to have to have some set of priorities and some discipline," Cohen told AFP.

"After a period of time, he'll have to see: Does he want to go back to China? Is he allowed to go back to China? What are the circumstances under which he could operate in China?"

Chen's situation recalls that of Fang Lizhi, the late dissident academic who spent more than a year in the US embassy after Tiananmen until Beijing allowed him to leave for the US. He died in exile last month.

Most dissidents who have sought political asylum abroad have escaped China often through its porous southern borders with Vietnam, Laos and Myanmar, as dissident writer Liao Yiwu did when fleeing last year.

The government has recently also allowed dissidents to leave voluntarily.

Writer Yu Jie, who penned a book highly critical of Prime Minister Wen Jiabao, was allowed to go earlier this year.

Liu Xiaobo's refusal to be sent into exile stems partly from the belief that he could be marginalised politically, supporters of the jailed 2010 Nobel Peace Prize winner have said.

Liu believes he is a more potent symbol in the struggle for democracy in China if he stays, they say.

Wei Jingsheng, who was freed from a 14-year jail sentence in 1997 and forced into exile as part of a bargain between China and the United States, said he would also rather be in his homeland.

"If I had my choice, of course I would rather be in China because you can do more when you are in China," Wei said.

"But when I left, the government made it clear that if I came back the only place I could live would be in jail."

Wei said making money was the first challenge for any exile.

"Making a living is the first step for any exile, but this is very difficult," said Wei, who now heads the Wei Jingsheng Foundation, which works to advance democracy in China.

"If you are successful in earning a living, then you may find no time for democracy and human rights work," Wei, 61, told AFP by phone from his US home.

"On the other hand, if you continue to advocate for democracy in China, you may have little time to get your life in order."

Scores of Chinese citizens were granted asylum overseas following the brutal crushing of the 1989 demonstrations, including student leaders like Wang Dan and Wuer.

But in a sign of the pull of their homeland, Wang, Wuer and other dissidents earlier this year addressed an open letter to the Chinese government urging that they be allowed to return home.