Facebook has yet to say when it might offer a local-language service for the China market, but it already boasts more than 100,000 members in its English-language China network, as well as alumni groups for the country's top universities, including Peking University and Fudan University.
The move also appears to be aimed at warding off the potential copyright tussles that have dogged Google in the fast-growing market.
Facebook.cn is registered by United States-based Facebook, according to search results on Wednesday on the Web site of government-backed China Internet Network Information Center.
The domain name facebook.com.cn, meanwhile, has been registered--to an individual working at a local Internet service provider--but the Web address redirects to Facebook's home page when entered into a Web browser.
The ".cn" suffix is commonly used for Chinese domain names. A message left on Facebook's media inquiries voice mail went unanswered.
Social-networking sites--which let members look up friends' Web pages, and share photos and videos--are flourishing in China, home to more than 162 million Internet users and second in size only to the United States.
Foreign venture capital firms have poured money into local social-networking companies, and overseas players,, have also set up their own services targeting Chinese Internet surfers.
But Google, fighting to consolidate its trademark globally, has come up against gmail.cn, which has been registered by a firm called ISM Technologies.
A legal source told Reuters earlier this year that ISM is refusing to sell the domain name to the Web search giant.
The name closely resembles Google's internationally known e-mail service, Gmail, and the colors in which the two logos are written are similar.