YouTube said on Friday that it's immediately blocking access around the world to channels associated with Russian state-funded media, a move that Russian media said violated the principle of freedom of the press.

The world's most used streaming video service, which is owned by Alphabet Inc's Google, said Russia's military operation in Ukraine now fell under its violent events policy and all those materials would be removed.

YouTube spokesman Farshad Shadloo said blocking Russian outlets was in line with the policy barring content that denies, minimizes or trivializes well-documented violent events.

Previously, YouTube had blocked Russia's state-backed channels RT and Sputnik across Europe.

Russian state media have called restrictions placed on them by distributors, which include app stores and other social media services, unjustified censorship.

"The blocking by YouTube is nothing but a new turn of an atrocious attack on one of the fundamental principles of a democratic society – that is freedom of the press," Sputnik said in a statement on Friday.

YouTube declined to specify which and how many channels had been blocked globally, or whether they ever would be restored.

Its policy states that channels may be permanently blocked for repeated violations, a single case of severe abuse, or when they are dedicated to violating content.