BEIJING, China (CNN) -- China has blocked the popular video-sharing Web site YouTube but did not offer a reason for the ban.
Google, which owns YouTube, said it began noticing a decline in traffic from China about noon Monday.
By early Wednesday, site users insider China continued to encounter an error message: "Network Timeout. The server at youtube.com is taking too long to respond."
"We do not know the reason for the blockage and we are working as quickly as possible to restore access to our users," said Scott Rubin, a spokesman for Google, which owns YouTube.
It's not the first time users in China have been unable to access the site. In March 2008, China blocked YouTube during riots in Tibet.
Many in the country speculated the latest ban may be an attempt to filter access to footage that a Tibetan exile group released. The videos show Tibetans being kicked and beaten, allegedly by Chinese police officers after the riots.