A Chinese internet cafe worker who posted pro-democracy articles online has been sentenced to eight years in prison, his lawyer says.

A court in the south-western city of Kunming jailed 27-year-old Cao Haibo for "subversion of state power", said his lawyer, Ma Xiaopeng.

He had set-up web chat groups on social issues, said a US-based rights group.

The case comes shortly before China's once-a-decade power handover at this month's Communist Party congress.

In the run-up to the opening of the congress on 8 November, authorities have clamped down on the work of political activists and dissidents in China, analysts say.

Cao was detained at his home in Yancheng in October last year after he set up a website and online chat groups advocating democracy and constitutional government, said Human Rights in China.

His trial was held in secret in May because the Kunming Intermediate People's Court said it involved state secrets, his wife, Zhang Nian, was quoted as saying.

She said the court had presented evidence that her husband had "created an online discussion group, and published articles on foreign websites".

Ms Zhang added that the trial had not been held in open and told the Associated Press that she was urging him to appeal.

"All he did was express his opinions on the internet. I think it is excessive of the court to give him such a harsh sentence for that," she said.

Kunming Intermediate Court has so far not commented on the case.