The Chinese government appears to have blocked access to the Google search engine, according to reports.
Google is hugely popular with users in China because it can run searches in the Chinese language.
But web masters from China contacted the BBC to tell them that access to the site had been blocked.
It is thought to be the first time Beijing has shut down access to an internet search engine, although provincial governments have attacked internet cafes recently and some foriegn news websites are blocked.
Licensed internet cafes must also install software blocking around half a million websites.
The Google ban is being widely debated on the web, with citizens pleading for access to the search engine.
There has been no official announcement from Beijing. Google officials in California could not be reached for comment.
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