Moscow police launched a series of raids on Wednesday on apartments and offices of jailed Russian opposition leader Alexei Navalny's family and associates, arresting his brother.
The searched locations included Mr. Navalny's apartment, where police detained his brother, Oleg, and a rented apartment where Navalny's wife, Yulia, has been living.
Video on the internet TV station Dozhd showed Yulia Navalny telling journalists from the window that police had not allowed her lawyer to enter the apartment.
The raids came four days before protests that Mr. Navalny's supporters have called for Sunday.
Demonstrations calling for his release took place in more than 100 cities across the nation on last Saturday, a strong show of rising anger toward the Kremlin. Nearly 4,000 people were reported arrested at those protests.
Other locations raided by police on Wednesday were the offices of Mr. Navalny's anti-corruption foundation and the studio that produces his videos and online broadcasts. The popular videos and broadcasts helped make Mr. Navalny into Russian President Vladimir Putin's most prominent and persistent foe.
There was no immediate police comment on the searches. Navalny associates said on social media that the searches were connected to alleged violations of epidemiological regulations from last week's mass protest in Moscow.
But “the real reason for the searches of Mr. Navalny's teams, relatives and office is Putin's crazy fear,” Mr. Navalny's team said in a message.
Mr. Navalny's challenge to Mr. Putin grew after he was arrested on January 17 upon his return from Germany, where he spent five months recovering from nerve-agent poisoning that he blames on the Kremlin.
Two days after his arrest, his organisation released an extensive video report on a palatial seaside compound allegedly built for Mr. Putin. It has been viewed tens of millions of times, further stoking discontent.
Mr. Navalny, the Kremlin's most prominent and durable foe, fell into a coma while aboard a domestic flight from Siberia to Moscow on August 20. He was transferred from a hospital in Siberia to a Berlin hospital two days later.
Labs in Germany, France and Sweden, and tests by the Organisation for the Prohibition of Chemical Weapons, established that he was exposed to the Soviet-era Novichok nerve agent.
Russian authorities have refused to open a full-fledged criminal inquiry, citing a lack of evidence that Mr. Navalny was poisoned.
In December, Mr. Navalny released the recording of a phone call he said he made to a man he described as an alleged member of a group of officers of the Federal Security Service, or FSB, who purportedly poisoned him in August and then tried to cover it up. The FSB dismissed the recording as fake.
Mr. Navalny's arrest and the harsh police actions at the protests have brought wide criticism from the West and calls for his release.
Russia's foreign ministry said on Wednesday that a statement by the Group of Seven foreign ministers condemning his arrest constitutes “gross interference” in Russia's domestic affairs.
