Beijing - A leading Chinese dissident was released from prison on Tuesday after serving 16 years of a 20-year sentence, the Hong Kong-based Information Centre for Human Rights and Democracy said.

Hu Shigen, 53, was arrested in May 1992 as he and other democracy activists were planning to distribute leaflets by remote-controlled planes in Beijing's Tiananmen Square.

The stunt was planned to coincide with the third anniversary of the ruling Communist Party's military crackdown on protesters on June 4, 1989.

Hu had also helped to found the China Liberal Democratic Party and the China Free Trade Union.

His early release from the 20-year prison sentence appeared to be linked to international pressure on the Chinese government, the Information Centre said.

Meanwhile, the Chinese Human Rights Defenders (CHRD) reported on Tuesday that prison staff had punished another prominent dissident, Hu Jia, after he pointed out illegal practices at Beijing's Chaobai prison.

Hu Jia was sentenced to three years and four months in prison in April for subversion.

The US-based Dui Hua Foundation said his arrest "cannot escape being connected to the Olympics."

CHRD said that Hu Jia, who suffers from cirrhosis of the liver, was made to sweep leaves in the prison grounds for up to seven hours a day after he pointed out that some punishments used by the prison "violate basic human dignity."

Prison staff also confiscated Hu Jia's letters to his family and a book on human rights sent by his wife, fellow activist Zeng Jinyan, the group alleged.

Police took Zeng and the couple's young child back to their Beijing apartment on August 23 after holding her at a hotel outside the city since August 7, apparently to prevent foreign journalists interviewing her during the Olympics.

Police are still keeping Zeng under "residential surveillance," a form of house arrest, the group said. (dpa)