Russia's mass media oversight agency, Roskomnadzor, has threatened to fine Google, Facebook and Twitter and ban their services unless the companies comply with Kremlin's demands to block "extremist material."

Alexander Zharov, head of the Roskomnadzor wrote letters to Google CEO Larry Page, Facebook Director for Relations in Russia Thomas Christensen and Twitter Director of Public Policy in Europe Sinead McSweeney, accusing the U.S.-based Internet giants of committing "lawless actions" by defying the country's blogging law, pro government newspaper Izvestia reported. The letters were sent on May 18. 

"Such letters have become a regular practice in our communication with the foreign Internet companies. Usually after sending such letters occur some progress in communicating," Roskomnadzor spokesman Vadim Ampelonsky said, according to Izvestia.

"We hope that in this case, the company will respond and fulfill the demands which they repeatedly sent," Ampelonsky added. 

Zharov's comments were made after powerful watchdog's deputy head Maxim Ksendzov issued a warning to the Google, Twitter and Facebook on May 6, demanding that any content which "contains calls for mass unrest [or] carrying out extremist activities" should be deleted, according to The Moscow Times.

The Roskomnadzor watchdog can fine a company up to 300,000 roubles for first time infringement, The Guardian reported. Companies can also be fined up to 500,000 roubles or receive a suspension of its operations for up to 30 days for second time violation. 

Bloggers with large followings must have their identities confirmed by the government and have an official registration, according to Reuters. A law passed last year authorized prosecutors to block websites which have information about unsanctioned protests and unrests. 

The Russian blogger's law requires Internet companies to delete pages that contain "extremist material," BBC News reported. Companies also need to transmit data on Russian bloggers who have more than 3,000 readers each day.