Russia will block access to Facebook next year unless the social network complies with a law that requires websites which store the personal data of Russian citizens to do so on Russian servers.
The threat was made by Russia's communications watchdog Roskomnadzor, the organisation which blocked access to LinkedIn's website last November in order to comply with a court ruling that found the social networking firm guilty of violating the same data storage law.
That case set a precedent for the way foreign internet firms operate in Russia and other companies are now under pressure from the regulator to comply with the law, which was approved by President Vladimir Putin in 2014 and entered into force in September 2015.
"Everyone needs to abide by the law," the Interfax news agency cited Roskomnadzor head Alexander Zharov as telling reporters on Tuesday.
"In 2018, everything will be as it should be for sure," he said, referring to Facebook.
"In any case, we will either get the law implemented or the company will cease to work on the territory of the Russian Federation as unfortunately happened to LinkedIn. There can't be any exceptions here."
Twitter had already notified Roskomnadzor that it would aim to localise the personal data of its users by the middle of 2018, Zharov said.
"We understand clearly that Facebook has a significant number of users on the territory of the Russian Federation," Mr Zharov was cited as saying.
"On the other hand, we understand that this is not a unique service, and that there are other social media."