A Chinese internet dissident who has been in detention since October has been formally arrested on charges of subversion.
The government has tried to crack down on internet dissent
The official Xinhua news agency said Du Daobin had written 28 internet articles aimed at the overthrow of China's socialist system.
Du had also campaigned for another internet activist, Liu Di, who was eventually released.
In recent months China has stepped up controls on internet use and access.
"Du had overstepped his legal rights of criticising government work and government functionaries with good intentions and viciously incited subversion of state power through fabrications," Xinhua quoted a police spokesman as saying.
Xinhua said Du was arrested in Hubei province, where he worked as a civil servant, in November. There was no mention of why the arrest has only just been announced.
There was some confusion over the circumstances surrounding Du's arrest because the New York-based group Human Rights in China said prosecutors had told police they had insufficient evidence with which to charge him.
In November last year Liu Di was released because of lack of evidence against her.
She had posted political essays online and was known by her online alias "Stainless Steel Mouse."
An internet petition has circulated in China in recent weeks, launched by more than 100 intellectuals and urging the national legislature to curb the practice of using subversion charges to suppress free speech.
Another 900 signatures have been added since the petition appeared.
A BBC correspondent in Beijing, Louisa Lim, says the petition is an example of the way in which the internet is being harnessed as a tool of social change.
But she says Du Daobin's formal arrest seems to be a sign that regardless of external pressure, the authorities are not ready to loosen their tight controls over cyberspace.