Yulia Navalny posted a picture of her inside a police van on her Instagram account, complaining the lack of light made for a bad photograph.
Around 90 protests are taking place, including in capital city Moscow.
Police called the rallies illegal and said that they would be “immediately suppressed.”
Navalny was arrested on his return to Russia from Germany on January 17, following a near-fatal poisoning with a nerve agent.
He was handed a 30-day jail term for violating the terms of a suspended sentence he was given in 2014 on fraud charges.
The 44-year-old says the charges are politically motivated.
The US, the European Union, France and Canada have urged his release. The EU has also imposed sanctions on Russia over Navalny’s arrest.
What is happening at the marches:
Thousands of people gathered in Moscow to march from central Pushkin Square to the Kremlin. The Interior Ministry estimated 4,000 people attended. News agency Reuters estimated the figure was likely 10,000.
“Mass arrests have already started on Moscow’s Pushkin Square — even before the official beginning of a protest demanding Navalny be let out of prison. Police seem to be grabbing people on the square at random. Dozens of arrests across the country at other protests already,” reported DW’s Russia correspondent Emily Sherwin.
Mass arrests have already started on Moscow’s Pushkin Square - even before the official beginning of a protest demanding #Navalny be let out of prison. Police seem to be grabbing people on the square at random. Dozens of arrests across the country at other protests already. pic.twitter.com/wGUE0iErDT— Emily Sherwin (@EmilyCSherwin) January 23, 2021
Prominent activist Lyubov Sobol was detained by police at the protest, broadcaster TV Rain reported.
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She is a lawyer for Navalny’s Anti-Corruption Foundation. She was also detained on Thursday along with Navalny’s spokeswoman Kira Yarmysh for calling on people to join the protests.
Politician Lev Shlosberg tweeted that he had been detained. He holds a seat on the Pskov Regional Assembly, in north-western Russia.
The day of protests kicked off in cities in Russia’s far east which is several time zones ahead of Moscow.
Navalny’s headquarters in Khabarovsk said on Twitter that several dozen protesters were rounded up by authorities in the city shortly after the demonstrations began. Video footage showed protesters braving freezing temperatures and chanting “Shame!” and “Bandits!”
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The protests in Khabarovsk are also focused on the arrest of the city’s popular former governor, Sergei Furgal.
In Vladivostok, video footage showed riot police chasing a group of protesters down the street.
Some braved temperatures as low as -50 degrees Celsius (-58 degrees Fahrenheit) in Siberian Yakutia to protest.
Protests calling for #Navalny to be released from prison are taking place all over Russia. His team has listed 93 cities. Several time zones away, people have been protesting in Yakutia in -50 C. This video shows in Vladivostok: “Let him go!” they chant. pic.twitter.com/bRFLJq142K— Emily Sherwin (@EmilyCSherwin) January 23, 2021
In several Russian cities there were mobile phone and internet network outages, the monitoring site downdetector.ru showed.
Twitter users in Russia also reported problems accessing the microblogging platform.
Communication problems were reported by users in the following cities: Moscow, St. Petersburg, Tyumen, Chelyabinsk, Yekaterinburg, Voronezh, Krasnodar, Rostov-on-Don and Saratov, the Russian independent online magazine Spektr.Press reported.
The authorities sometimes interfere with mobile communication networks to make it harder for protesters to communicate among themselves and share video footage online.
Russia cracks down on organizers, social media
Ahead of the protests, Russia’s media watchdog Roskomnadzor accused platforms of hosting content encouraging and organizing the protests.
It threatened fines if they did not remove content encouraging minors to participate in the demonstrations.
Authorities also said they had launched a criminal investigation against Navalny’s supporters for urging minors to attend illegal rallies on social networks.
The Investigative Committee for the Novosibirsk Region in central southern Russia opened a criminal case on incitement to mass riots, Russian independent media outlet MediaZona reported on Friday.
They reportedly detained a 20-year-old resident for his role in organizing protests.
Navalny’s associates also urged Russians to take to the streets despite official pressure, promising financial help to protesters given fines.
In a push to galvanize support, Navalny’s team also released a video about an opulent palace on the Black Sea they alleged belonged to Russian President Vladimir Putin - something the Kremlin denied. The clip had been viewed more than 60 million times as of late Friday.