MOSCOW - Russia on Thursday threatened to block Facebook for allegedly publishing ads for illegal designer drugs on its website.
The state media watchdog said it had added Facebook to a blacklist and that the social network would be blocked within three days if the violations were not resolved.
Facebook responded swiftly to the threat, within hours removing the ads which led users to a site selling the designer drug "Spice" and other synthetic narcotics.
A spokesman for the California-based company told the Russian tech site Digit.ru that the ads were the result of a "bug".
The tussle was the latest episode in what appears to be a continuing crusade by Russian conservatives to challenge US web giants in Russia.
The investigation into Facebook was prompted by a complaint from Ruslan Gattarov, a senator from the ruling party, United Russia, who has recently campaigned against alleged breaches of Russians' rights by major US Internet firms.
This "has shown that there are no untouchable companies - if the law is broken, they must react, and if they don't, they can expect to be blocked," the senator told the ITAR-TASS news agency after Facebook pulled the ads.
Gattarov had said earlier this week that he wanted Facebook to face a fine of several million dollars.
The ads had apparently appeared on the site for some time, but authorities only acted after Gattarov formally complained, independent channel TV Rain reported.
Gattarov on Thursday called for Facebook to open an office in Russia. The absence of permanent premises for the company in the country has long been a gripe for the Russian government.
Gattarov, who heads the presidential council on developing Internet use, has in recent months called for the law enforcement agencies to investigate Apple and Twitter over alleged violations of users' privacy and argued that Gmail violates Russia's constitution.
Gattarov has been a particularly vocal critic of the US National Security Agency's (NSA) surveillance programmes, revealed by fugitive Edward Snowden. In August, he founded a website to raise funds for Snowden, after Russia granted him asylum.