Google was working late Sunday night to restore its YouTube video service in China, after the Chinese government blocked access to the site, which was flooded with videos of clashes between police and protesters in Tibet and other cities.

The search advertising giant said it was investigating "reports of users being unable to access YouTube" in China, and trying to get the site back online.

"We are looking into the matter, and working to ensure that the service is restored as soon as possible," a spokesperson for YouTube, which is owned Google, told Portfolio.com by email.

Attempts to load YouTube in China