A state television employee burst on to Russia’s main state television evening news broadcast on Monday to protest against Vladimir Putin’s invasion of Ukraine, the largest sign yet of simmering discontent at the three-week war.

Marina Ovsyannikova, an editor at Channel One, appeared for a few seconds live on air holding a sign that said “Stop the war — Don’t believe propaganda — They’re lying to you” and chanting “Stop the war! No to war !”

Though the channel cut the feed after a few seconds, Ovsyannikova’s unprecedented intervention was an extraordinary act of defiance after Russia ramped up already draconian censorship laws when the war began in late February.

Police detained Ovsyannikova under a new law that criminalises acts such as “discrediting the Russian armed forces” and spreading “fake news” of the conflict, said Pavel Chikov, whose Agora legal defence foundation is representing Ovsyannikova.

Though the strictest punishments carry a potential prison sentence of up to 15 years, Chikov said Ovsyannikova was likely to be fined Rbs30,000 to Rbs60,000 ($250 to $500).

Channel One told state newswire Ria Novosti it was investigating the incident.

In a video recorded beforehand and posted by Ovd-Info, a website that monitors arrests at protests, Ovsyannikova blamed Putin, Russia’s president, for the war and said she was ashamed of her role in it as a Channel One employee.

“What’s happening in Ukraine is a crime, and Russia is the aggressor. The responsibility for this aggression lies with one man: Vladimir Putin,” Ovsyannikova said.