Russia launched administrative action against Facebook Inc. and Twitter Inc.on Monday for failing to comply with its data laws, a move that comes just days after Facebook removed the accounts of what it said were two misinformation campaigns based in the country.

Communications watchdog Roskomnadzor, the federal executive body responsible for censorship in media and telecommunications, said the social-media networks hadn’t submitted any formal and specific plans or submitted an acceptable explanation of when they would meet the country’s requirements that all servers used to store Russians’ personal data be located in Russia. Roskomnadzor said it had sent the companies a letter on Dec. 17 advising them of the need to comply with the law and giving them 30 days to provide “a legally valid response,” Russian news agency Interfax reported.

As such, “Today, Roskomnadzor begins administrative proceedings against both companies,” the watchdog said.

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The move raises concern that the social-media giants could face future restrictions or be blocked. On Thursday, Facebook said it would expand efforts to crack down on misuse of its service by removing some 500 pages and accounts linked to what it said were two Russia-based misinformation campaigns.

Vadim Ampelonsky, a spokesman for Roskomnadzor, told the television channel Russia 24 that Facebook and Twitter could be fined for not providing information to the watchdog.

“We expect to hold them administratively liable,” Mr. Ampelonsky said.

Representatives for Facebook and Twitter in the U.S. didn’t immediately respond to requests for comment.

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Russia’s law on the storage of personal data came into force in September 2015, according to the state-controlled news agency TASS. Last April, Roskomnadzor’s head, Aleksandr Zharov, said the agency would check, by the end of 2018, whether Facebook was complying. If it wasn’t, then the question would arise “about blocking the social network,” Interfax reported.

Mr. Zharov also promised to check Twitter for compliance with Russian legislation. According to Interfax, the company had notified Roskomnadzor that it had started localizing the databases of Russian citizens in the second half of 2018.

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