Access to 51.com blocked

One of China's largest social networking websites could not be accessed for undisclosed reasons yesterday.

51.com, a community portal, similar to Facebook, went offline around 4 pm, sparking rumors that the site is the latest victim of government efforts to clamp down on objectionable content on the Internet.

The website, with more than 100 million users, has received backing from major venture capital investment firms, including Sequoia Capital China and Redpoint Ventures, also an investor in MySpace.com.