(AFP) - Police detained dozens of Russians paying tribute to opposition leader Alexei Navalny on Saturday, as his spokeswoman accused authorities of stalling the release of his body to relatives.

The 47-year-old Kremlin critic died in an Arctic prison on Friday after spending more than three years behind bars, prompting outrage and condemnation from Western leaders and his supporters.

His death, which the West has blamed on the Kremlin, deprives Russia's opposition of its figurehead just a month before elections poised to extend President Vladimir Putin's grip on power.

Makeshift memorials and small protests in memory of the deceased leader on Saturday were swiftly broken up by Russian police, who rights groups say have detained over 200 people so far.

AFP reporters saw two people being detained at a pop-up tribute in central Moscow, while hundreds of tearful mourners laid flowers in the snow.

"Alexei Navalny's death is the worst thing that could happen to Russia," said one note left among the flowers.

Navalny's lawyer and mother Lyudmila arrived in the remote northern town of Salekhard on Saturday, where they had been told his body was being kept at a local morgue.

"It was closed despite the prison saying that it was open and that Navalny's body was there," Navalny's team said on Telegram.

His spokeswoman, Kira Yarmysh, accused officials of "lying" about examining the body in an attempt to avoid handing it over to his family.

"It's obvious that the killers want to cover their tracks," Navalny's team said in a follow-up post on Telegram.

- Putin 'responsible' -

After initially pushing back at accusations they were to blame, the Kremlin made no mention of his death on Saturday, despite an angry chorus of condemnation from Western leaders.

G7 foreign ministers meeting in Munich held a minute's silence for the leader on Saturday, while US President Joe Biden pointed the blame at Putin.

"Make no mistake, Putin is responsible for Navalny's death," he said on Friday.

Russian Nobel Peace Prize winner Dmitry Muratov said Navalny's death was "murder" and that he was "tortured and tormented" for all of the three years he spent in prison.

In the capital Moscow, police detained at least 15 people who had been laying flowers at a monument for victims of Soviet repression, the independent media outlet Sota said.

In one video posted by the outlet, a woman could be heard screaming as a crowd of police officers forcefully detained her, to chants of "shame" from onlookers.

Another showed a group of people in plain clothes removing flowers from a monument in the capital's Lubyanka Square overnight, while police blocked off the area.

Navalny's death was announced by Russia's federal penitentiary service, which said Friday he "felt bad after a walk" and died.

Russian news agencies reported that medics from a local hospital arrived within minutes and spent more than "half an hour" trying to resuscitate him.

Navalny's wife, Yulia Navalnaya, said she held Putin personally responsible and called on the international community to "unite and defeat this evil, terrifying regime".

- 'I'm not afraid' -

One of Navalny's lawyers, Leonid Solovyov, told the Novaya Gazeta newspaper that he was "normal" when another lawyer saw him on Wednesday.

In footage of a court hearing from his prison colony on Thursday, Navalny was seen smiling and joking as he addressed the judge by video link. State media reported he raised no health complaints during the session.

Speaking at the Munich Security Conference hours after news of her husband's death, Yulia Navalnaya said Putin and his entourage would be "punished for everything they have done to our country, to my family and to my husband".

Navalny, who led street protests for more than a decade, became a household name through his anti-corruption campaigning.

His exposes of official corruption, posted on his YouTube channel, racked up millions of views and brought tens of thousands of Russians on to the streets, despite harsh anti-protest laws.

He was jailed in early 2021 after returning to Russia from Germany, where he was recovering from a near-fatal poisoning attack with Novichok, a Soviet-era nerve agent.

In a string of cases, he was sentenced to 19 years in prison on charges widely condemned by rights groups and seen in the West as retribution for his opposition to the Kremlin.

His return to Russia despite knowing he would face jail brought him admiration around the world.

"I'm not afraid and I call on you not to be afraid," he said in an appeal to supporters as he landed in Moscow, moments before being detained on charges linked to an old fraud conviction.

His 2021 arrest spurred some of the largest demonstrations Russia had seen in decades, and thousands were detained at rallies nationwide calling for his release.

- 'Don't do nothing' -

From behind bars, Navalny was a staunch opponent of Moscow's full-scale military offensive against Ukraine, but watched on, helplessly, as the Kremlin dismantled his organisation and locked up his allies.

Dozens of his top supporters fled into exile and continued to campaign against the offensive on Ukraine and repression inside Russia.

Late last year, Navalny was moved to a remote Arctic prison colony nicknamed "Polar Wolf" in Russia's Yamalo-Nenets region in northern Siberia.

He said in January that his daily routine included prison walks in freezing temperatures.

Since being jailed, he spent more than 300 days in solitary confinement, where prison authorities kept him over alleged minor infringements of prison rules.

The last post on Navalny's Telegram channel, which he managed through his lawyers and team in exile, was a tribute to his wife posted on Valentine's Day.

In a documentary filmed before he returned to Russia, Navalny was asked what message he wanted to leave to the Russian people should he die or be killed.

"Don't give up. You mustn't, you can't give up," he said.

"All it takes for evil to triumph is for good people to do nothing. Therefore, don't do nothing."

© Agence France-Presse