A new law that went into effect in Russia on Friday takes "internet censorship in Russia to a new level," press freedom advocacy group Reporters without Borders (RSF) says.

Under the new law, Russian authorities can theoretically isolate the country from parts of the global internet. The government says the law aims to keep the Russian network functioning smoothly in the event of a crisis or external attack. However, critics warn that the new rules will allow censorship of content that is unwanted by the Kremlin under the pretext of an undefined "security threat."

Digital freedom activist groups such as RSF say the law will allow authorities to block content without telling the public what has been blocked and why.

"It proves that the Russian leadership is ready to bring the entire network infrastructure under political control in order to cut off the digital information flow whenever needed," said Christian Mihr, the executive director of RSF Germany.

"Even if the new regulations may not be fully enforceable, they show how extensively internet freedom is threatened in Russia," Mihr said.

Thousands have demonstrated against the law, which was signed by President Vladimir Putin in May.

Read more: Russian propaganda: 'A multitude of lies and absurd news'

Technical problems

An additional feature of the law is the creation of an independent Russian Domain Name System (DNS) that goes into effect in January 2021. The DNS means that Russian users will no longer determine what website they are sent to when they enter an address. The state will thus be able to direct them to fake websites or to none at all.

However, it remains unclear whether the isolation planned by Russian authorities is technically feasible. Among other things, it requires all Russian providers and other service providers to install technology allowing the media authority, Roskomnadzor, to block data traffic. So far, most internet service providers lack the technology.

Read more: Russian activists: 'There are a lot of laws aimed at the restriction of human rights'

Russia's business association, the Russian Union of Industrialists and Entrepreneurs, has warned that the law could lead to a "catastrophic failure" of communications networks in Russia.

It also said that it would be difficult to separate Russia from foreign servers responsible for carrying much of the business transaction activity of Russian corporations.

RSF ranks Russia 149th out of 180 countries in terms of press freedom.

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