Russian opposition leader Alexei Navalny and hundreds of his supporters were arrested in central Moscow on Saturday during nationwide rallies against President Vladimir Putin’s inauguration for a fourth term in office.
Police grabbed Mr Navalny, 41, soon after he showed up at the rally in Pushkin Square, as some shouted "Shame" in Ukrainian, a famous slogan of the Kiev uprising that ousted a Kremlin-backed regime in 2014.
More than 700 people were arrested in Moscow, where riot police were seen beating protesters with truncheons and dragging them into police vans. Tear gas was also briefly used, according to reports.
A helicopter hovered overhead in an apparent bid to drown out chants.
Similar demonstrations were organised in cities across Russia, with more than 1,600 people detained by police by early evening according to the OVD-Info independent monitor.
Mr Navalny, who was barred from challenging Mr Putin in the March presidential election, had called on Russians to stage the rallies under the slogan "Not our Tsar."
Along with opposition leader Nikolai Lyaskin, Mr Navalny was detained “for organising an unauthorised public event,” according to a police statement cited in local news reports.
An official count by Moscow police put the size of the rally at least 1,500 people. They warned they would use force and "impact munition" against the demonstrators.
Scuffles also broke out between Mr Navalny's supporters and pro-Kremlin activists who descended into the square in an apparent effort to sabotage the opposition demonstration.
Saturday's demonstration was the first major event organised by Mr Navalny since the presidential election on March 18, which the opposition leader encouraged voters to boycott.
"Craven old man Putin thinks he is a tsar," Navalny said on Twitter ahead of the demonstrations.
Authorities in some Russian cities issued permits for demonstrations, though many did not and mass arrests ensued.
In Saint Petersburg, several thousand people marched along Nevsky Prospect, the city's main thoroughfare, chanting "Putin is a thief" and "Down with the tsar".
When police tried to stop the unsanctioned march, protesters pelted them with eggs and water bottles, an AFP reporter said. More than 200 were arrested.
In the Urals city of Chelyabinsk, more than 160 people were detained by mid-afternoon. In Yakutsk, some 75 were reported arrested.
Observers had expressed fears that the protests could lead to mass arrests after similar rallies in 2012 led to a huge crackdown on the protest movement.
In May 2012, tens of thousands took to the streets to protest Mr Putin's inauguration for a third Kremlin term, with rallies descending into clashes with police.
Criminal charges were brought against around 30 demonstrators and many of them were sentenced to prison terms of between 2.5 years and 4.5 years.
Mr Putin, who is in the final days of his third term before his swearing-in ceremony on Monday, won with almost 77 percent of the vote.
Before his reelection, Mr Putin had secured his place in Russian history as the nation’s longest-serving leader since Joseph Stalin. He has been in power since 2000.