MOSCOW (Reuters) - Russia's communications watchdog Roskomnadzor said on Friday it had blocked access to the Viber messaging app, the latest in a line of social media services to be banned by Russian authorities.

In a statement, Roskomnadzor said the block was related to a violation of rules concerning the prevention of terrorism, extremism, and drug dealing.

Rakuten Group, which owns Viber, did not immediately respond to a request for comment.

Hiroshi Mikitani, the founder and chief executive of Rakuten Group had touted the messenging app as a way to counter what he called Russian propaganda.

"Unlike other social media, we've made it crystal clear we're going to block all these fake news and propaganda of Russia," Mikitani told Reuters in a Zoom interview during a visit to Kyiv last year.

(Writing by Felix Light, Editing by Louise Heavens and Christina Fincher)