A new Google 'question and answer' page has become inaccessible to users in mainland China on Tuesday.
The news comes less than a month after the Chinese government renewed the company's internet licence, after Google promised to adhere to Chinese censorship laws.
Google Wenda is designed to allow Chinese users to post questions that can then be answered by others, similar to the Answers service offered by Yahoo.
A Google spokesperson told news agency Associated Press that the company had found no problems with its server in Hong Kong, suggesting that the Chinese communications ministry has deliberately blocked the service from the mainland.
"If you are noticing there is a blockage you would need to ask the government, as it would be an issue at their end," she said.
The Chinese government has refrained from issuing any statement on the matter, and has not responded to Google's attempts discuss the issue.
Reuters reports that before it became inaccessible, the questions page had been filled with anti-communist party queries, including questions asking when China would have its next Tiananmen-style uprising, as well as abuse aimed at revered former leader Mao Zedong.