A woman holding an anti-war sign ran on to the set of a Russian evening news programme on the state-controlled Channel 1 on Monday evening.
The sign, clearly visible behind the presenter, read: “No war, stop the war, don’t believe the propaganda, they are lying to you here.”
The woman has been named as Marina Ovsyannikova, an editor at the channel.
Russian TV news is tightly controlled by the Kremlin and reflects only the Russian version of events in Ukraine.
Ms Ovsyannikova is believed to be in police custody.
Her voice could be heard during the broadcast saying, “No to war! Stop the war!” before the programme director cut early to a recorded news report.
Access to the BBC has also been restricted inside Russia, leading the corporation to issue guidance over how to continue using its services.
Russia’s media watchdog accused the BBC and other foreign broadcasters of the “deliberate and systematic circulation of materials containing false information”.
Many social media sites have also been blocked, further restricting the number and diversity of news sources available to people inside Russia.
Facebook and Twitter have been restricted for several days, while Instagram – which is particularly popular in Russia – was blocked on Monday, although many Russians have found ways round the restrictions.
Source: BBC