The founder of VKontakte (VK), Russia's largest social network, has claimed that the website is now "under the complete control" of close associates of Russian president Vladimir Putin.

Pavel Durov claimed in a post on VK that he was fired from the website without warning and only learned of his dismissal through media reports.

"It's interesting that shareholders did not have the courage to do it directly," Durov wrote. "I learnt about this mysterious dismissal from the press."

The site has been transferred to the "complete control" of Igor Sechin and Alisher Usmanov, two Russian oligarchs with close ties to Putin, according to Durov.

Durov resigned as CEO of VK earlier this month but later retracted the resignation and hinted that it was part of an April Fool's Day joke. His resignation letter did allude to his discontent with the direction the social network was taking.

"It has become increasingly complicated to stick to the principles we once founded our social site upon," Durov wrote.

Crackdown on dissent

VK is Europe's second largest social network and attracts 45 million daily active users. It has come to be known as the "Russian Facebook" due to its similar layout and function though Durov's libertarian principles differ from those of Facebook founder Mark Zuckerberg.

He has favoured the use of encryption to protect users' privacy and has been outspoken against mass surveillance, even inviting NSA whistleblower Edward Snowden to join VK in 2013.

When ordered to shut down pages operated by activists rioting against the Kremlin in 2011, Durov refused. Speculation following his departure now points to greater state control of the site.

"Probably, in the Russian context, something like this was inevitable, but I'm happy we lasted seven and a half years," Durov wrote in his most recent post.

"We did a lot. And part of what's been done can't be turned back."