Wikipedia has shut down its Russian language website and blacked out its logo in protest at a bill that would allow the state to block access to blacklisted websites.
"Imagine a world without free knowledge," the online encyclopedia company said in a statement on its closed site. It argued that amendments to be discussed in parliament today (Wednesday) "could lead to the creation of extrajudicial censorship of the whole Russian-language Internet".
The amendments to an existing information law are being promoted as a crackdown on child pornography in particular, but the Ru.Wikipedia.org site warned that they could "prompt the creation of a Russian version of the Great Firewall of China".
The amendments, passed in Russia's Parliament the Duma last Friday call for the creation of a federal register that would rule on websites carrying banned information, and oblige site owners and providers to close down the offending sites.
The bill comes as part of an apparent trend to use the pliant Duma lower house dominated by the ruling United Russia party to introduce laws that can be used against the opposition.
It has recently pushed through legislation increasing fines for protesters and stigmatising internationally-funded NGOs as "foreign agents".
The legislation highlights websites carrying child pornography, promoting drug use and encouraging children to commit suicide, saying the decision to blacklist these would be taken by a federal agency.
It would also blacklist sites using Russia's vague extremism laws, which can be enforced by the ruling of any district court, as well as provides for a whole site to be blacklisted over the content of just one page.