Russia has blocked more than 16 million internet protocol addresses in its attempt to ban the popular encrypted messaging app Telegram, leading to interruptions in the service of major websites and media.

A court ordered the service blocked in Russia after it refused to hand over its encryption keys to state security agencies like the FSB.

But attempts to block it temporarily took down gaming services including Microsoft Xbox, the social network Odnoklassniki, the Viber messaging service, the note-taking app Evernote, the site of radio station Govorit Moskva, the food delivery service Ptichka and many others on Tuesday.

“It's hard to count the casualties before the smoke above the battlefield has cleared, but I think there's a huge number,” said Sarkis Darbinyan, a lawyer for the internet freedom group RosKomSvoboda.

Telegram remained functional as of Tuesday night and said it had gained hundreds of thousands of new users.

“We promised our users 100 per cent privacy and would rather cease to exist than violate this,” Telegram founder Pavel Durov, a 33-year-old entrepreneur who fled Russia after he was forced out of his VK social network by Kremlin-linked owners, wrote on the messenger on Tuesday.