Reuters reports that Mr. Du Daobin, from Yingcheng in Hubei province, was detained this week after placing banned information on the Internet.
The report quotes Du's wife: "The state security told me he was held at Xiaogan police detention center, but when my sister went there to give him some clothes and a blanket, they denied he was there."
Du took part in an online petition on behalf of jailed cyber dissident Liu Di, who was detained in Beijing in November 2002. Du's writings have been outlawed in China, but are available on overseas portals and websites.
China routinely blocks websites deemed to carry illegal or immoral content.