A Chinese journalist jailed in 2007 after reporting on corruption and due to be released this year has had his sentence extended, rights activists and his lawyer said Friday.

Qi Chonghuai, a veteran journalist who once wrote for the China Work Safety Production News, was sentenced to an extra eight years in jail after pledging to continue his anti-corruption campaign, Human Rights in China reported.

The US-based organisation said Qi told the mayor of Tengzhou in the eastern Chinese province of Shandong he would not give up his fight against corruption when the official visited him in jail recently.

The prosecution has since reactivated the original extortion case against Qi and sentenced him to an additional eight years based on alleged new evidence, Human Rights in China said.

In 2007, Qi was sentenced to four years in jail for extortion, a charge he denied.

He later accused his police interrogators of beating him in jail, and of threatening to kill him and call his death suicide.

"Qi has to stay in prison for another eight years. He can appeal, but there is little hope off success," the journalist's lawyer Liu Xiaoyuan told AFP by telephone.

Although China's central government has strongly condemned corruption amongst its ranks, journalists and ordinary citizens who expose local graft often end up in jail.