Russia’s media watchdog has written to Twitter, Google and Facebook warning them against breaking Russian Internet laws as well as a spokesman said on Thursday they risk if they don’t obey the rules being blocked.

“In our letters we often remind (businesses) of the effects of breaking the laws,” said Roskomnadzor spokesman Vadim Ampelonsky.

He added that, due to the encryption technology used by the three companies, Russia had no means of blocking unique sites and so could just bring down unique content it deemed in breach of law by blocking access to their services that were whole.

Putin, a former KGB spy, once described the Internet as a job of the CIA, emphasizing deep distrust between Washington and Moscow, whose ties now are badly stressed.

He assured not to get the Net under total government control, since Putin returned to the Kremlin for a third period in the year 2012, but Kremlin critics view the Internet laws as a piece of a crack down on freedom of speech.

A law gives the right to block with no court judgement sites with info about demonstrations which never have been sanctioned by authorities to Russian prosecutors.

Under other laws, bloggers have their identities verified by a government agency and with big followings must go through an official enrollment process.

Facebook says it reacts to government data requests about its users that match international standards of legal process and comply with local laws and business policies.

A business web site that releases figures on data requests are handled by Facebook reveals this past year it rejected both of two Russian government requests for advice on its users.

Twitter had a similar reaction rate in the United States but rejected 108 Russian government requests in the 2nd half of this past year, based on data on the government Transparency Report website of the company’s.

In its semi-annual Transparency Report, Google said it supplied some info on users in response to 5% of 134 Russian government requests made in America much less than in the 2nd half of 2014.

“We realise they’re filed under U.S. authority. However , I believe in this case they need to show equivalent regard to national laws,” Ampelonsky said.

In the event the companies don’t pay a lot more attention to Russian government requests for information, he added, “we’ll have to use sanctions”.