Kremlin critic Navalny detained after landing in Moscow

Russian opposition leader Alexei Navalny was arrested at a Moscow airport on Sunday as he tried to enter the country from Germany, where he has spent five months recovering from nerve agent poisoning that he blames on the Kremlin.

Mr Navalny's detention at passport control in Moscow's Sheremetyevo airport was widely expected because Russia's prisons service said he had violated parole terms from a suspended sentence on a 2014 embezzlement conviction.

The prisons service said he would be held in custody until a court ruled on his case. No date for a court appearance was immediately announced. The service earlier said that it would seek to have Mr Navalny serve his three-and-a-half-year sentence behind bars.

Mr Navalny, 44, who is President Vladimir Putin's most prominent and determined foe, brushed off concerns about arrest as he boarded the plane in Berlin.

"It's impossible; I'm an innocent man," he said.

The arrest raises tensions in Russia as it approaches national parliament elections this year, in which Mr Navalny's organisation is expected to be active in trying to defeat pro-Kremlin candidates.

Mr Navalny decided to leave Berlin of his own free will and was not under any apparent pressure to leave from Germany.

"This is a real act of bravery for Alexei Navalny to return to Russia, given that government agents already tried to kill him once," Human Rights Watch executive director Kenneth Roth tweeted.

"But he understandably wants to be part of the pro-democracy movement in Russia, not a dissident in exile."

Alexei Navalny kisses his wife Yulia as he is detained by police at passport control after arriving at Sheremetyevo airport
Alexei Navalny kisses his wife Yulia as he is detained by police at passport control after arriving at Sheremetyevo airport (Mstyslav Chernov/AP)

Mr Navalny has sizable popularity in Moscow. Many supporters went to Vnukovo airport on Sunday where his flight was scheduled to land, though it was diverted to Sheremetyevo without explanation.

The OVD-Info organisation that monitors political arrests said at least 37 people were detained by police at Vnukovo, where the arrivals hall had been blocked off and prisoner transport vehicles were parked outside.

The independent newspaper Novaya Gazeta and opposition social media reported on Sunday that several of Mr Navalny's supporters in St Petersburg had been removed from Moscow-bound trains or been prevented from boarding flights late Saturday and early Sunday, including the co-ordinator of his staff for the region of Russia's second-largest city.

Mr Navalny fell into a coma while aboard a domestic flight from Siberia to Moscow on August 20. He was transferred from a hospital in Siberia to a Berlin hospital two days later.

Labs in Germany, France and Sweden, and tests by the Organisation for the Prohibition of Chemical Weapons, established that he was exposed to a Soviet-era Novichok nerve agent.

Russian authorities insisted that the doctors who treated Mr Navalny in Siberia before he was airlifted to Germany found no traces of poison and have challenged German officials to provide proof of his poisoning.

Alexei Navalny
Mr Navalny has been a thorn in the Kremlin's side for a decade (AP)

Russia refused to open a fully-fledged criminal inquiry, citing a lack of evidence that Mr Navalny was poisoned.

Last month, Mr Navalny released the recording of a phone call he said he made to a man he described as an alleged member of a group of officers of the Federal Security Service, or FSB, who purportedly poisoned him in August and then tried to cover it up.

The FSB dismissed the recording as fake.

Mr Navalny has been a thorn in the Kremlin's side for a decade, unusually durable in an opposition movement often demoralised by repressions.

He has been jailed repeatedly in connection with protests and has been twice convicted of financial misdeeds in cases that he said were politically motivated.

He suffered significant eye damage when an assailant threw disinfectant into his face and was taken from jail to a hospital in 2019 with an illness that authorities said was an allergic reaction but that many suspected was poisoning.

Mr Navalny's wife Yulia is surrounded by people as she leaves Moscow's Sheremetyevo airport
Mr Navalny's wife Yulia is surrounded by people as she leaves Moscow's airport (AP)

A lawyer by training, he began his rise to prominence by focusing on corruption in Russia's murky mix of politics and business.

In 2008, he bought shares in Russian oil and gas companies, so he could push for transparency as an activist shareholder.

Mr Navalny's work to expose corrupt elites had a pocketbook appeal to the Russian people's widespread sense of being cheated.

Russia's state-controlled television channels ignored Mr Navalny, but his investigations of dubious contracts and officials' luxurious lifestyles got wide attention through the back channels of YouTube videos and social media posts that often showed his sardonic sense of humour.

In 2013, he came second in the race for Moscow mayor behind the candidate of Mr Putin's powerbase United Russia party.

That established him as a formidable force and a worry to the Kremlin.