Russia's internet monitoring agency has blocked 13 web pages linked to the Ukraine protest movement which helped oust the country's Russia-leaning president last week.
Roskomnadzor said in a statement published online that it had been ordered by the general prosecutor's office to shut down the pages on Russia's leading social media website, VKontakte.
The largest pro-demonstration group, which has more than 500,000 members, was not accessible to users on Russian territory today.
While much of Russian media is state-controlled, the internet has so far remained largely free from censorship and has provided an active forum for anti-government criticism.
Pro-Russia activists recaptured administrative headquarters in the Ukrainian city of Donetsk and flew the Russian flag from its roof.
ITV News' Europe Correspondent describes the tense atmosphere surrounds a central government building in Donetsk .
New footage obtained by ITV News shows Russian troops firing warning shots as Ukrainian soldiers approached during a tense stand-off today.