A Russian court placed opposition leader Alexei Navalny under house arrest for at least two months on Friday and barred him from using the internet or speaking to the media.
The court said Navalny, an outspoken critic of President Vladimir Putin and a leader of anti-Kremlin protests in 2011-2012, had violated rules barring him from leaving Moscow.
Navalny denounced the ruling as baseless and said it was meant to silence him.
"I believe the new measures are based on trumped up grounds in order to restrict my political activities," Navalny, 37, said in court.
Navalny, who gained prominence with blog posts alleging government corruption, emerged from the biggest protests of Putin's 14-year rule as the main opposition leader and a potential future challenger in elections.
He is serving a five-year suspended sentence on a theft conviction that will keep him out of a 2018 presidential vote, and has been charged with theft and money-laundering in a separate case that has not come to trial.
Kremlin opponents say Putin is clamping down on dissent after engineering the release of long-jailed oil tycoon Mikhail Khodorkovsky and two members of punk protest band Pussy Riot before the Sochi Olympics, which ended last week.