Russia may hit Facebook with a hefty fine for failing to delete content Moscow deems illegal.
That's according to a statement by communications regulator Roskomnadzor.
It says the penalty could total 10% of the social network's turnover in the country.
Over the past year Russia has been ramping up pressure on foreign tech companies.
That's part of a move to assert greater sovereignty over its part of the internet.
It includes an effort to make companies store Russians' personal data within the country.
On Wednesday (September 29) Moscow threatened to block YouTube.
That after it removed state backed broadcaster RT's German-language channels from its site.
There was no comment on the latest reports from Facebook.
Roskomnadzor has already opened 17 cases against the network this year for failing to take down banned content.