‘Putin wants to kill more’: Grim warning from politician poisoned and locked up by Russia

A high-profile Kremlin critic has made a series of extraordinary remarks about Vladimir Putin following Russia's decision to move troops into Ukraine in a move that Western leaders say amounts to an invasion.

Outspoken opposition figure Alexei Navalny, currently serving a three-and-a-half jail sentence in Russia, likened the president to a "drunken grandfather" and accused him of wanting to "kill".

Navalny, a lawyer and anti-corruption activist who survived a suspected assassination attempt, has previously organised large demonstrations against Putin calling for reform against corruption in Russia.

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"Putin and his senile thieves from the [Russian] Security Council and United Russia are the enemies of Russia and its main threat, not Ukraine and not the West," Navalny said on Twitter.

"Putin kills and wants to kill more."

Navalny referred to a meeting of the Security Council on Monday, where officials made unsubstantiated - and at times outlandish - claims which served as a precursor to Russia's military escalation.

Accusations included suggesting Ukraine is developing nuclear weapons, and that it is committing a genocide in eastern Ukraine.

The opposition leader also described Putin's almost hour long speech on Monday evening - in which he appeared to lay out some of his reasons for invasion - as "truly insane".

Navalny's comments are especially stark given his history with Putin, whose regime has designated him as an extremist. In 2020, Navalny blamed Putin after he was poisoned with the Russian nerve agent Novichok.

His poisoning is not the first time vocal critics of Putin have been targeted; Russian defector Alexander Litvinenko was poisoned with plutonium in London in 2006, and in 2018 Sergei Skripal - a former Russian military officer and double agent for the UK - and his daughter were poisoned with Novichok in Salisbury.

In 2015 a public inquiry found that Putin was likely to have ordered Litvinenko's poisoning, and in 2019 a spokesperson for then prime minister Theresa May said there was "irrefutable evidence" Russia was responsible for the Salisbury poisonings.

Read more: Ministry of Defence posts map of how Putin could invade Ukraine on Twitter

Navalny was also imprisoned by Putin when he returned to Russia after receiving treatment for the poisoning in Germany in 2021, after Russia claimed he had to serve a historic suspended sentence for fraud. Navalny rejected the justification, saying it was manufactured; his imprisonment was condemned by the European Court of Human Rights.

He faces a further 15 years behind bars on embezzlement charges in a trial many have said is politically motivated.

"Thanks to Putin, hundreds of Ukrainians and Russian citizens may die now, and in the future, this number may reach tens of thousands," Navalny continued on Tuesday.

"Yes, he will not allow Ukraine to develop, he will drag it into the swamp, but Russia will pay the same price."

Navalny's remarks come as the West moves to sanction Russia in an attempt to encourage de-escalation.

However Putin announced on Tuesday afternoon that he has authorised troops to fight abroad - which could pave the way for a broader attack.

Boris Johnson confirmed five Russian banks are set to be sanctioned by the UK along with three "very high net worth" Russians.

Read more: Russia-Ukraine cyberattacks risk ‘spillover effect’ to the U.S. and other world powers

Elsewhere, Germany took the dramatic move to halt Nord Stream 2 - a highly controversial gas pipeline between Russia and Germany which would have created greater dependence on Russian gas.

Watch: Putin critic Alexey Navalny faces prison term extension at Russian correctional colony