Russia's top online social network was banned on Friday from distributing content across the country, raising concerns of a clampdown on a forum used by President Vladimir Putin's opponents to organize protests.
The ban on VKontakte follows more than a month of pressure on the company and its founder, Pavel Durov, who has drawn comparisons with Facebook's Mark Zuckerberg for building an online network with 210 million registered users.
Durov, 28, has had brushes with the authorities since refusing to comply with an order by the Federal Security Service, a successor to the Soviet KGB, to shut down forums used to organize protests since December 2011.
Things started to go wrong for Durov last month, when he was implicated in a traffic incident in the city of St Petersburg in which a policeman was slightly injured.
He denied being involved but, instead of complying with a summons to testify as a witness in the case, left the country, sources close to the company say. Durov has not been seen in public or posted on his VKontakte page since April 24.
VKontakte spokesman Georgy Lobushkin said he had no information regarding the decision by regulator Roskomnazdzor.
VKontakte's website was still working in Moscow, but some media reports said it had been blocked in parts of the country. According to the reports VKontakte had faced criticism from Russia's ombudsman for children's rights for hosting child pornography. At least one of the Boston Marathon bombing suspects also had a page on VKontakte.