Two months after Vladimir Putin once again assumed the post of Russian president, the long-feared crackdown on his critics appears to have begun. The internet bill due to be considered by parliament on Wednesday is, say activists, the latest sign of growing repression of civil freedom in Russia.

The bill calls for the creation of a federal website "nolist". Internet providers and site owners would be forced to shut down any websites on this list. According to Wikipedia authors on Tuesday, the bill will "lead to the creation of a Russian analogue to China's great firewall".

The bill's backers in Putin's United Russia party argue that the amendments to the country's information legislation are aimed at child pornography and sites that promote drug use and teen suicide.

But critics, including the Russian-language Wikipedia, say the legislation could be used to boost government censorship over the internet.

In protest, the Russian-language Wikipedia site shut down for 24 hours on Tuesday. The Wikipedia logo was crossed out with a black rectangle, and the words "imagine a world without free knowledge" appeared underneath.

The Russian parliament's consideration of the controversial internet bill comes amid a host of other initiatives that activists say make up the biggest attempt since the Soviet era to silence government critics.

Before the start of the summer recess at the end of the week, MPs are to consider a bill that obliges non-governmental organisations receiving foreign funding to brand themselves "foreign agents".

Amendments to boost fines for defamation are also on the agenda. This year, fines for protesting have been heavily increased.

"This is the first time that we've seen a large-scope crackdown on people who dare challenge the government and express anti-Putin sentiments," said Masha Lipman, an analyst at the Moscow Carnegie Centre. "We have never had this before, but then we never had political rallies like this in post-Soviet Russia."

The laws are a response to the mass protests that have drawn tens of thousands of Russians on to the streets following Putin's declaration of returning to the presidency late last year, Lipman said. "There are two options – you either yield to the demands [of the protesters] or you crack down. Putin is not the type who yields to demands," Lipman said. "Putin's whole regime is based on control, on securing the ruling group from any challenge or contest."

She added: "The Kremlin showed some tolerance until the presidential election, but as soon as Putin had his election safely past him, the government began to crack down. Now there are more and more developments on a daily basis."

The internet bill prompted widespread outrage across the Russian network. On Tuesday, the blogging platform LiveJournal joined the protest against the bill.

The Russian justice ministry maintains a register of more than 1,000 websites that have been classed as "extremist" and ordered to be shut down.

The bill appears to realise the biggest fear of opposition activists – a platform that has so far remained relatively free has now become the target of Kremlin ire.

Anton Nossik, a Russian internet expert, wrote in his blog: "For the last 12 years I've lived in happy confidence that the Russian authorities would be smart enough not to censor the internet. But the situation, unfortunately, is changing."

With Russia's main state television channels under the control of the government, and its few free newspapers unable to be distributed across a vast country with poor infrastructure, the internet has become a growing source of free information. But that may now be changing.

According to thousands of emails leaked this year by the Russian arm of Anonymous, the Kremlin, until now, has limited its efforts to control the internet by paying commenters affiliated with the youth group Nashi to leave pro-government comments on certain websites.

Blogs and social networks have been a key aspect of the organisation of the street protests that have swept Moscow recently.

Alexey Navalny, a leading opposition figure, was relatively unknown until he began an anti-corruption blog. On his site on Tuesday he wrote: "The Kremlin swindlers have understood that paid commenters and an army of bots can't help them in any way with their 'ideological struggle for the internet'."

He backed Wikipedia's day-long shutdown, a move that echoes similar action, in January, by the English language Wikipedia concerning protest against the US Congress's consideration of the Stop Online Piracy Act.