Li Shaomin's hopes to return to Hong Kong had been watched carefully by local pro-democracy figures, who had expressed fears he would be barred.
They had said if he had not been allowed to come back, Hong Kong's autonomy, left in place when Britain returned its former colony to China four years ago, would have been compromised.
Li had lived in Hong Kong until the Chinese authorities arrested him in the nearby mainland city of Shenzhen on Feb. 25. Li obtained a Ph.D. in sociology from Princeton University in 1988 and became an American citizen in 1995.
The Hong Kong government said in a statement Monday night that Li arrived in Hong Kong in the afternoon and was allowed to enter in the evening.
The statement stressed that no one in Hong Kong can spy against China. Li's employer, the City University, has been vague about how it would treat him as an employee if he came back. He has been teaching marketing there since 1996.
The statement quoted a government spokesman as saying there would be no comment on Li's status entering Hong Kong because "it was not the government's policy to comment on individual cases."
Li Shaomin, 44, flew to the United States last week after he was deported from China following his conviction on charges he damaged Chinese national security and spied for Taiwan.
No evidence against him has been publicly released.
Hong Kong's human rights activists had worried from the outset that Li would not be allowed to return here even though many dissidents are allowed to live in Hong Kong.
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Qin Guangguang, paroled by Beijing last week following pressure from Washington, went first to visit his sick mother in the southwestern province of Sichuan because he fears China will not allow him back once he leaves.
A friend who asked not to be identified said Qin told him he would probably leave for the United States this week.
Qin, 45, was sentenced to 10 years in prison on spying charges with Gao Zhan, a U.S.-based Chinese sociologist who also was freed on medical parole. Gao returned Thursday to the United States.
Qin, a Chinese citizen with permanent U.S. residency, had taught at American universities and was working for a pharmaceutical company in Beijing when he was detained in December.
The three scholars were released ahead of Secretary of State Colin Powell's weekend trip to China. Powell had voiced concern about the detentions.
But Gao, Li and Qin aren't the only scholars facig jail time in China. Another scholar, Qu Wei, was sentenced to 13 years in jail last week.
Among those still in custody are Wu Jianmin, a U.S. citizen and writer from New York, and Xu Zerong, a historian trained at Harvard and Oxford Universities who was working in Hong Kong.
A group of 35 Chinese activists last week issued an appeal addressed to Powell to ask Beijing for medical parole for dissident Xu Wenli, the Information Center said.
Xu's wife said on Thursday that he suffers from hepatitis and chronic back pain.
Xu, 58, was sentenced in 1998 to 13 years in prison for trying to form an opposition political party.
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