Russia issued an arrest warrant on Tuesday for Yulia Navalnaya, the widow of Alexei Navalny, accusing the exiled opposition figure of being part of an “extremist organisation”.

A court said it had “approved the request of the investigators and decided a preventive measure in the form of detention for two months”.

Ms Navalnaya has vowed to continue the work of her husband, Russian leader Vladimir Putin’s main opponent, who died in an Arctic prison in February.

She is no longer in Russia, but her exact location has not been made public.

Ms Navalnaya slammed the warrant in a statement, saying: “Vladimir Putin is a killer and a war criminal. He belongs in prison.”

The activist’s team also dismissed the allegations.

Ms Navalnaya “was arrested (in absentia!) for ‘being a member of an extremist community’ by the infamous Basmanny court of Moscow,” wrote Leonid Volkov, Navalny’s former chief of staff, on X, formerly Twitter.

“Quite a recognition of Yulia’s determination to continue Alexei’s fight!” he added.

Mr Navalny’s organisations have been outlawed in Russia, labelled an “extremist” group and put on an official “terrorist” list.

Ms Navalnaya, an economist, stood by her husband as he galvanised mass protests in Russia, flying him out of the country when he was poisoned before defiantly returning to Moscow with him in 2021, knowing he would be jailed.

Following his death, Ms Navalnaya vowed to take up her late husband’s work and has lobbied against Putin’s government from abroad.

During Russian elections in March, Ms Navalnaya called for mass protests against Putin, urging supporters to form long queues outside polling stations.