Veteran Chinese rights activist Chen Wei was sentenced Friday to nine years in jail for "subversion", his lawyers said, in one of the harshest penalties handed down in a crackdown launched this year.

Chen, who was a leader of the 1989 Tiananmen democracy protests, was among dozens of activists detained in February in the wake of political upheaval in the Arab world that sparked calls for anti-government demonstrations in China.

The court in Suining city in southwest Sichuan province convicted Chen, 42, after a trial lasting less than three hours over essays he had written that were critical of the Communist Party, China Human Rights Defenders said.

The sentence, for "inciting subversion of state power" was one of the toughest sentences handed down so far to an activist detained in this year's crackdown, the activist group said.

Chen does not plan to appeal the sentence, his lawyers told AFP.

"He does not intend to appeal because he feels this is a political sabotage and he does not want to perform any more pantomimes," Liang Xiaojun told AFP.

After the sentence was read out in court, Chen shouted out that he was innocent and declared "democracy will definitely prevail and dictators will definitely fall", Liang said.

Another lawyer, Zheng Jianwei, said the severe sentence was "terrifying" because it showed the government was willing to use trumped-up charges to silence critics.

"He is not guilty. He criticised the party and there was no law banning that," Zheng said.

"If everybody keeps quiet about politics and political reform then the country will not progress. It will be as harmonious as the party wants."

Chen has campaigned against human rights abuses in China for years.

He was imprisoned after the 1989 Tiananmen democracy protests and was a signatory to the Charter 08, a bold petition signed by thousands calling for political reform in one-party Communist-ruled China.

Activist group Amnesty International criticised the harshness of the sentence and called for Chen's immediate release.

"This extraordinarily long sentence is clearly retaliation for Chen Wei's peaceful advocacy of human rights and we are calling for his immediate and unconditional release," Catherine Baber, Amnesty's deputy Asia-Pacific director told AFP.

The charge of subversion is often used to put away government critics -- jailed Nobel Peace Prize winner Liu Xiaobo was convicted on the same charge in 2009.

The plight of human rights activists in China has come under the spotlight since Liu was awarded the prestigious prize in 2010, with the West pressing for the release of all political prisoners.

Chen's sentencing comes a week after prominent human rights lawyer Gao Zhisheng was sent back to prison just as his five-year suspended sentence was set to expire this week.