Vladimir Putin's main political opponent Alexei Navalny 'missing' after removal from Russian prison colony

Vladimir Putin's main political opponent Alexei Navalny is missing after being removed by officials from a prison colony in Russia, his allies say.

The alarm was raised after the politician failed to show for a scheduled court appearance via videolink on Monday, with friends saying they had also not heard from him in six days.

The 47-year-old has been behind bars since January 2021 on what supporters say are politically-motivated charges.

Mr Navalny was transferred to the IK-6 jail in Melekhovo, east of Moscow, last year, but his spokeswoman Kira Yarmysh said staff there had now confirmed he had been removed from the facility.

She added on X, formerly Twitter: "Where they have taken him, they refuse to say."

Ms Yarmysh said prison officials claimed he had not appeared via videolink as expected because of "electricity problems".

It comes just days after Mr Putin announced he would stand for re-election next year - potentially keeping him in power until at least 2030.

Mr Navalny's aide Leonid Volkov also posted on X that the timing was "0% coincidence and 100% direct manual political control from the Kremlin."

He added: "It is no secret to Putin who his main opponent is in these 'elections'. And he wants to make sure that Navalny's voice is not heard."

The politician has been one of the Russian president's fiercest critics in recent years and helped organise large-scale anti-Kremlin protests.

But he was arrested in January 2021 after returning to Moscow from Germany, where he had been recuperating from being poisoned by a nerve agent.

Mr Navalny blamed the Kremlin for the attack, an allegation denied by Russian authorities.

Mr Navalny lost an appeal in September against a 19-year prison term for alleged extremist activity which was handed down in August and came on top of an existing 11-and-a-half year sentence for fraud and other charges.

Following the latest sentencing his allies said they had been expecting him to be moved to a "special regime" prison colony, the harshest grade in Russia's prison system, but had not been given any further information.

Supporters said staff at another prison colony, IK-7, had also denied they were holding Mr Navalny.

However, it can take weeks for prisoners to be transferred between jails and families are sometimes not told about their relatives' whereabouts until they reach their destination.

A Russian lawyer, who wanted to remain anonymous, told Sky News legal representatives usually submit an official request to find out where their clients are.

"Sometimes they [the colony authorities] simply show you on the database right on the spot, sometimes they just name the region where they are," they said, but added that responses varied.

Mr Navalny denies all charges against him.

The Kremlin is yet to comment, although it has previously accused opposition figures such as Mr Navalny of having links with Western intelligence agencies which they say want to destabilise Russia.