The BBC's Ade Akintonwa: This will further damage China's international reputation

Zhang Shanguang's conviction comes just days after three prominent dissidents received long jail sentences sparking an international outcry.

Human rights campaigners said Mr Zhang was accused of threatening national security after he gave information about farmers' protests to Radio Free Asia.

Mr Zhang was jailed after the Tiananmen Square protests

They said the dissident's family was barred from the closed trial in Huaihua city in Hunan province, which lasted less than two and a half hours.

The court also stripped Mr Zhang of his political rights for five years after his release, according to reports.

The New York based group, Human Rights in China, said the activist was accused of "illegally providing intelligence to overseas enemy organisations and people".

Correspondent Carrie Gracie: "Another heavy blow to the democracy movement"

In an interview with US-funded Radio Free Asia in March, Mr Zhang spoke about demonstrations by farmers against excessive taxes.

Beijing considers the network hostile to communist rule and blocks its broadcasts. In June it refused to grant visas to its reporters to cover President Bill Clinton's visit to China.

Mak Hoi Wah of pro-democracy Hong Kong Alliance: "A foolish act by China"

Mr Zhang, 45, was detained five months ago after he tried to set up a pressure group to help laid-off workers.

He had previously served a seven year sentence after he was arrested in a nationwide crackdown following the demonstrations in Beijing's Tiananmen Square in 1989.

International outcry

His trial follows those of Xu Wenli, Qin Yongmin and Wang Youcai, three of China's most prominent dissidents.

They were sentenced this week to 13, 12 and 11 years respectively for trying to establish the China Democracy Party to challenge communist rule.

Mr Jiang has vowed to get tough

In Hong Kong, activists marched to China's official Xinhua News Agency office on Sunday to demand the release of the three jailed dissidents.

The trials have sparked worldwide condemnation with the US calling the sentences deplorable.

But the Chinese authorities have warned they will continue to take a tough line and dismissed the criticism as foreign interference.

'We'll nip subversion in the bud'

The crackdown comes just 11 weeks after China signed the United Nations International Covenant on Civil and Political Rights which guarantees freedom of speech.

But President Jiang Zemin said last week that subversive activities would be "nipped in the bud" and said China would never tolerate Western-style democracy.

Shortly after the warning, China targeted the arts and entertainment industries, mandating harsh punishments for those found guilty of "inciting to subvert state power".

The new rules cover writing, music, movies, television, video recordings and computer software, outlawing material that "endangers social order".