Petr Versilov had difficulty seeing, speaking and moving when he fell ill and was hospitalised in Moscow.

Prominent anti-Kremlin activist Pyotr Verzilov, a member of the Pussy Riot protest band, has been hospitalised following suspected poisoning, the group said, adding that his “life is in danger”.

Verzilov, 30, staged a brief pitch invasion during the football World Cup final in Moscow in July along with three women affiliated to the anti-Kremlin punk band.

He is also the publisher of Mediazona, a Russian online news outlet which focuses on human rights violations inside the country’s penal system.

“Our friend, brother, comrade Petr Verzilov is in reanimation. His life is in danger. We think that he was poisoned,” Pussy Riot said on its official Twitter account on Wednesday.

Our friend, brother, comrade Petr Verzilov is in reanimation. His life is in danger. We think that he was poisoned. https://t.co/BYVl4rir1a — 𝖕𝖚𝖘𝖘𝖞 𝖗𝖎𝖔𝖙 (@pussyrrriot) September 12, 2018

Verzilov had difficulty seeing, speaking and moving when he fell ill late on Tuesday and was hospitalised in the Russian capital, according to a report on the news site Meduza.

Meduza cited Veronika Nikulshina, who it said was Verzilov’s girlfriend, described how he had been rushed to the hospital after he started to lose his eyesight and ability to talk and walk.

However, Sergei Smirnov, editor-in-chief of Mediazona, struck a more cautious note confirming on social media that Verzilov was in hospital but saying nobody knew his diagnosis, making it difficult to understand what was going on.

Verzilov and the others served a 15-day sentence for running onto the pitch in front of President Vladimir Putin and other high-ranking officials wearing police uniforms during the final, a stunt they said was meant to promote free speech.

Pussy Riot rose to prominence in 2012 when its members were jailed for staging a protest against Putin in a Russian Orthodox cathedral in Moscow. The group has since become a symbol of anti-Kremlin protest action.