MOSCOW Messenger service WhatsApp faces a maximum fine of 4 million roubles (51,500) after Russia accused it of failing to delete banned content, state-owned news agency RIA reported on Friday, citing a Moscow court.

Although WhatsApp's parent company Meta Platforms Inc was last year banned in Russia as an "extremist" organisation, the messenger app - which is widely popular in Russia - has not previously been threatened with legal proceedings for failing to remove prohibited information.

The RIA report did not specify what information WhatsApp had allegedly failed to delete. It said the administrative case was filed by communications regulator Roskomnadzor.

At the outset of its military campaign in Ukraine, Russia introduced harsh new military censorship laws under which technology companies including Google, Wikipedia and Discord have been fined.

($1 = 77.7205 roubles)

(Reporting by Reuters; Editing by Mark Heinrich)