Russia's state communications regulator said on Friday it was taking punitive measures against five foreign IT companies for violating online content laws, which could require search engines to include a disclaimer about the violations.
The regulator, Roskomnadzor, said it was imposing measures against ByteDance's TikTok, Telegram messaging service, Zoom Video Communications, chat tool Discord and Pinterest.
In a statement, Roskomnadzor said that the measures were in response to the companies' failure to remove content that it had flagged as illegal, and would remain in place until they complied.
None of the companies immediately responded to written requests for comment.
Roskomnadzor did not specify precisely what measures would be taken. Russia's dominant Yandex search engine already carries a disclaimer for some other websites that reads: "Roskomnadzor: website violates Russian law".
"Roskomnadzor has decided to apply enforcement measures ... in the form of internet users being informed by search engines about the companies' violations of Russian legislation," the regulator said.
Russia has fined several, mostly foreign tech firms for not deleting content it deems illegal. It has also warned sites against violating a law passed in early March that prohibits "discrediting" the armed forces, with a sentence of up to 15 years.
On Tuesday, Russian courts fined Amazon's live streaming unit Twitch 2 million roubles ($33,900) and Telegram 11 million roubles for hosting content that Moscow said contained "fake" information concerning events in Ukraine.
Russian lawmakers in July approved a bill providing for stricter penalties for foreign internet companies, including the search engine disclaimer.
