Thousands of people turned out in cities across Russia on Sunday to demand the release of detained opposition leader Alexei Navalny.
Police have, so far, detained more than 1,500 demonstrators, according to monitoring group OVD-Info.
More than 300 people were rounded up in Moscow alone — including Navalny's wife, Yulia Navalnaya, the Kremlin critic's allies said on social media.
Police closed off the capital's Lubyanka square near the Kremlin where protesters had planned to gather at midday local time (0900 UTC/GMT). Instead, organizers urged demonstrators to gather at another central square.
DW's Moscow correspondent Emily Sherwin says authorities have gone to great lengths to prevent the protests from taking place: "They've blocked off a huge section of the capital ... blocked roads, redirected buses, seven metro stations are closed," she said.
"Protesters aren't able to get there. Navalny's team has now ... posted new meeting points so it seems the authorities and the protesters may be playing a game of cat and mouse."
Navalny's team said rallies were planned in more than 100 cities across Russia's 11 time zones.
Hundreds of arrests in Russia's far east
The first protests kicked off in the country's far east, where police in the city of Vladivostok blocked protesters from reaching the center. Video footage showed people linking hands and chanting "Putin is a thief" as they gathered in temperatures of around minus 13 degrees Celsius (8.6 degrees Fahrenheit). More than 100 people were detained there.
Thousands of people also attended a rally in the eastern Siberian city of Novosibirsk, where around 90 were detained, according to OVD-Info. Local media reported that clashes had broken out between police and protesters in the central city of Chelyabinsk, where another large march was underway.
Thousands of people were arrested a week ago during nationwide demonstrations in support of Navalny, who was arrested on January 17 after returning from Germany. The outspoken Kremlin critic was poisoned with the nerve agent Novichok in Siberia last
summer and had been receiving treatment in Berlin.
Unprecedented security measures
Police warned that Sunday's rallies were unauthorized and would be broken up, while the Interior Ministry said those taking part could face jail time.
Authorities introduced unprecedented security measures in the capital in a bid to restrict protesters' movements. They shut down seven metro stations in the city center, blocked off streets around the Kremlin and ordered restaurants and stores to stay closed.
Police also asked Moscow cafes to turn off their internet connections ahead of the protests.
The US embassy in Moscow voiced alarm on Twitter at the "multiple reports of journalists in press vests being detained" and urged Russia to "respect international #humanrights commitments."
Crackdown on Navalny allies
Last week, hundreds of thousands of demonstrators protested in support of Navalny. A record 4,002 people were arrested for their involvement in the protests.
Navalny, 44, was immediately arrested upon his arrival in Moscow earlier this month and sentenced to pretrial detention.
Many of the opposition politician's associates have also been targeted in recent days. His brother Oleg, top aide Lyubov Sobol and three other people were sentenced to two months of house arrest on Friday for allegedly violating coronavirus regulations during last weekend's mass demonstrations.