Google on Friday reported unexplained disruptions to its service in China.
"We've checked and there is nothing wrong on our end," a Google spokeswoman told AFP.
An online tool that tracks outages or disruptions to the California-based Internet giant's services showed online traffic in China plummet mid-day.
The disruption followed reports that Chinese Internet users have evaded censors to take potshots at President Hu Jintao's assessment of his performance in a farewell speech.
Hu launched a week-long Communist Party congress in Beijing on Thursday with a speech that touted his political leadership, but also warned in stark terms of worsening problems such as corruption that threaten the party's legitimacy.
Users of the country's hugely popular microblogging sites -- the only major forum for relatively open expression in the tightly controlled country -- reacted with cynicism.