LiHai, 50, was sentenced in 1996 on charges of divulging state secrets after he compiled lists of people imprisoned in the wave of arrests that followed the bloody June 4 crackdown on demonstrators in Tiananmen Square.

"He came back this morning," Li's mother, Gong Liwen, said in a telephone interview. "It's a very happy occasion but there's still no freedom.

Every time we go out, there are people watching us."

Gong's telephone was repeatedly disconnected during the interview, one of the ways activists say the government monitors them. Hundreds, if not thousands, died when Chinese troops attacked protesters who had gathered for weeks on the square in the centre of Beijing to agitate for a more open political system and an end to corruption.

As the 15-year anniversary of the event approaches, China's government appears to be trying to prevent any public memorial by tightening their watch on political activists and relatives of people killed in the crackdown by detaining them at home and tapping their telephones. New York-based Human Rights in China said police have warned Gong to ensure that his release from Liangxiang Prison in Beijing does not spark any "unanticipated events."

"Li Hai has already suffered unreasonably for peaceful activities that are not even considered crimes in free and democratic societies," the group's president, Liu Qing, said in a statement.

"We urge the Chinese government not to use the June 4th anniversary as a pretext to deprive Li Hai of his liberty any longer than fulfilment of his sentence demands." An official on duty at the prison said he "wasn't clear" about the case. A woman who answered the telephone at the Beijing police headquarters said she had no information. Li, then a graduate philosophy student at the elite Peking University, was a strong advocate of the democracy movement. He spent 18 months in prison soon after the protests, the New York-based rights group said.

Upon his release, he helped other political prisoners by contacting their families and making their plight known to the international community, the group said. He was arrested again in 1995 for those activities and sentenced to nine years in prison.

Li was subjected to severe physical and mental abuse and spent most of his sentence in solitary confinement or under close monitoring, the group said. Gong said Li's health had improved in the last two months because he was allowed to exercise.

BEIJING -- A Chinese court sentenced a U.S.-based political activist Thursday to five years in prison on charges of spying for rival Taiwan in a case that prompted protests by Washington.

Yang Jianli, who was detained in 2002, was also convicted of illegal border crossing after a trial in a Beijing court, the official Xinhua News Agency said. The one-sentence report did not give any other details.

Yang, a Chinese citizen with permanent U.S. residency, was in China to meet with dissidents and protesting laid-off workers when he was stopped while boarding an airline flight using a false identity card.

Yang, 40, lives in suburban Boston and runs the Foundation for China in the 21st Century, an advocacy group calling for political change in China. His family said he was using a friend's identity card to travel because the Chinese government refused to renew his passport.

Yang will decide within five days whether to appeal, once a written verdict is issued, said his lawyer, Mo Shaoping.

"As his lawyer, I entered a not guilty plea for him," Mo said. "I do not agree with this verdict."

The government hasn't released any of its evidence against Yang.

The verdict was announced by the official Xinhua News Agency, which said he was tried in a closed court in line with Chinese national security laws. A man who answered the phone at the Beijing No. 2 Intermediate People's Court refused to give details or his name.

Yang is one of a series of foreign-based Chinese who have been convicted in recent years on charges of spying for Taiwan, which split with the mainland in 1949.

Yang's sentence includes the two years he has been held since his April 26, 2002, detention in the southwestern city of Kunming, Mo said.

Last month, members of the U.S. Congress issued a letter addressed to Chinese President Hu Jintao calling Yang's detention "extraordinarily inhumane." China has rejected U.S. protests as an "interference in the judicial process of China."

The U.S. Embassy in Beijing had no immediate comment on his conviction.

On Thursday, the Chinese Foreign Ministry defended the handling of the case.

"The Chinese judicial departments have been trying this case and made a sentence in complete accordance with the law," said ministry spokesman Liu Jianchao.

Liu said Yang accepted money from Taiwan for collecting intelligence, used a false identity and tried to obtain state secrets. He said Yang was allowed to meet with his lawyers numerous times and "made a full defense."

The charges against Yang apparently stem from four $100 grants to student researchers by a group that he founded in 1992 while attending the University of California-Berkeley, said Jared Genser, a Washington-based lawyer for his family.

Chinese prosecutors say the grants by the China Youth Development Foundation were funded by someone in the Taiwanese government, but no evidence was given in court, Genser said.

He said the research projects were "innocuous," including one on improving papaya-growing techniques in China.

While the prison sentence was "somewhat mild compared to what we were expecting," Genser said China has "so much larger problems to deal with than Yang Jianli."

"Yang Jianli has been punished enough," he said. "The time has come for his case to be resolved."

The legal deadline for a verdict passed last December with no announcement. Genser contends that that makes Yang's continued detention illegal.

Yang's supporters and family have appealed to the U.S. and Chinese legislatures for help in gaining his release, saying Yang has been held in solitary confinement and handcuffed in the State Security Bureau's detention center in Beijing.

His wife, Christina Fu, says he has been denied exercise and reading materials. She said his treatment worsened after he started a small protest of his imprisonment in March.

Mo, who met with Yang this week, said his client's physical condition appeared "all right."

He is out of solitary confinement and now shares a one-room cell with two other inmates, Mo said. He said only Yang's brother has been allowed to visit recently.

Wang Bingzhang, another U.S.-based dissident, was sentenced to life in prison last year on charges of spying for Taiwan and plotting a possible bomb attack against China's embassy in Thailand.