By JESSICA E. VASCELLARO and GEOFFREY A. FOWLER

Access to GoogleInc.'s YouTube service was blocked by Chinese authorities, as the video-sharing site continues to wrestle with governments offended by some of its content.

A YouTube spokesman said as of Tuesday evening it hadn't been contacted by the Chinese government and was working to restore the service, which had been disrupted for more than 24 hours.

The site has been temporarily censored in at least a dozen countries, according to YouTube, including Turkey, where a ban remains in effect. Such incidents are buffeting YouTube's attempts to expand into new markets, particularly China, home to the world's largest number of Internet users—nearly 300 million, according to the government.

YouTube faces stiff competition in China from domestic video-sharing sites such as Tudou.com, which are less likely to get blocked in their entirety because they restrict political or racy content that might draw fire from the government.