Russian opposition leader Alexei Navalny has been detained at home ahead of a planned unauthorised protest in Moscow, his wife says.
“Alexei has been arrested in the entrance to our block of flats,” Yuliya Navalnaya wrote on Twitter, adding “our plans haven’t changed”.
Mr. Navalny earlier called on his supporters to attend anti-corruption rallies across the country.
At least 100 people have reportedly been arrested by police in riot gear.
In a live broadcast by the Russian liberal TV channel Dozhd, protesters in St Petersburg could be heard shouting “shame” as they were detained by police. Among those arrested was Maxim Reznik, the city’s legislative assembly deputy.
Prominent activist Daniil Ken said he was arrested as he left his home in St Petersburg. He urged people to join a rally at the city’s Champ de Mars square. “Go for me, please!” he tweeted.
Police earlier detained several people at demonstrations in the cities of Vladivostok, Blagoveshchensk and Kazan.
Mr. Navalny, who intends to stand for the Russian presidency next year, was due to attend the unauthorised rally in central Moscow later on Monday.
He was earlier granted permission to hold a rally at Sakharova Avenue but changed the location on the eve of the demonstration to Tverskaya Street, near the Kremlin.
One of the groups participating in the Moscow rally, which is over government plans to demolish Soviet-era apartment blocks in the city, said it would hold its protest on Sakharova Avenue as planned.
Permission has been granted for demonstrations in 169 locations across the country, some of which will be broadcast live on the Navalny Live YouTube channel. The main rallies are expected to be in St Petersburg and Moscow.
The protests coincide with a series of official events – including festivals, concerts and military enactments – due to take place across the country to mark Russia Day, the national holiday dedicated to the 1990 declaration of sovereignty.
Despite being a public holiday in Russia, turnout in Monday’s protests has so far been lower than similar rallies led by Mr. Navalny in March, which led to hundreds of arrests.
Those protests were the largest since 2012, drawing thousands of people – including many teenagers – to rallies nationwide, angered by a report published by Mr. Navalny that accused Prime Minister Dmitry Medvedev of corruption.