A Moscow court has thrown out jailed Kremlin critic Alexei Navalny's appeal against a nine-year prison sentence that he and his allies condemn as politically motivated.

Moscow City Court ruled to "leave the sentence without changes" and for it to enter into force immediately, meaning that Navalny will be transferred to a strict regime prison colony to serve out his term, after he was found guilty in March of embezzlement and contempt of court.

Navalny had joined the hearing at a Moscow court via video-link wearing a black prisoner uniform and a fur-collared winter jacket and appeared composed and joked about problems with the sound system.

The hearings started last week but Navalny was granted a week's postponement so he could have a family visit.

The hearings come as Russian authorities seek to silence remaining government critics and Moscow pushes on with its military campaign in neighbouring Ukraine.

During today's live court hearing, he criticised President Vladimir Putin, casting him as a madman who had started a "stupid war" in Ukraine based on lies.

"This is a stupid war which your Putin started," Navalny told the court.

"This war was built on lies," he said.

"One madman has got his claws into Ukraine and I do not know what he wants to do with it - this crazy thief," Navalny said of President Putin.

The Kremlin has repeatedly dismissed Navalny's claims about Mr Putin, who it says has won numerous fair elections in Russia since 2000 and remains by far the country's most popular politician.

A vocal critic of the Russian President, Navalny in late March had his jail time extended to nine years after he was found guilty of embezzling donations to his political organisations and contempt of court.

Alexei Navalny is seen on a screen during the verdict in his embezzlement and contempt of court trial on 22 March 2022

His lawyer Olga Mikhailova told the court the sentence should be annulled as it is "unjust" and "contradicts international law", while the prosecutor called it "legal and justified".

Navalny told the court his case was heard in prison on the pretext of Covid restrictions although the relevant Moscow court was functioning.

"The Covid restrictions only applied to me," he said.

He also alleged his legal team "caught judge (Margarita) Kotova right in the middle of the trial calling someone from the presidential administration".

Navalny is already serving two-and-a-half years in a prison around 100km east of Moscow for violating parole on old fraud charges.

Navalny rose to prominence as an anti-corruption blogger and, before his imprisonment, mobilised anti-government protests across Russia.

In 2020, he narrowly survived a poisoning attack with Novichok, a Soviet-designed military-grade nerve agent. Despite accusations from Navalny, the Kremlin denied any involvement.

Alexei Navalny pictured on a plane returning to Russia from Germany on 17 January 2021

He was arrested last year on his return from treatment in Germany, sparking widespread condemnation abroad and sanctions from Western capitals.

Navalny's political organisations across the country have since been declared "extremist" and shut down.

His key allies have fled Russia and several are wanted by Russian authorities on criminal charges.