A Moscow court on Tuesday froze the assets of protest leader Alexei Navalny as part of an investigation into alleged fraud and money laundering by him and his brother Oleg.
The Basmanny District Court agreed with a petition by investigators and "ordered a freeze on assets belonging to the two brothers Navalny," spokeswoman Natalia Romanova told AFP.
She did not explain which particular assets had been affected.
The petition was filed in court on Monday as part of the case into Navalny's alleged theft of nearly a million dollars from a French cosmetics firm, she said.
Navalny appeared surprised at the news, saying he was not notified. "I don't know which of my assets the court arrested," he tweeted.
Navalny and his lesser-known brother Oleg were indicted last month in a fraud and laundering case, less than two weeks after a court in the northern Kirov region suspended a five-year sentence the opposition leader received for supposedly defrauding a timber firm.
The second case against Navalny alleges that he and his brother stole a total of 30 million rubles ($940,000) and laundered 21 million rubles from cosmetics company Yves Rocher and a Russian firm MPK.
Navalny, 37, rose to prominence during the massive anti-Vladimir Putin protests in the winter of 2011-12.
He won 27 percent of the vote in September polls for Moscow mayor against a Kremlin-backed incumbent, proving himself as a serious political contender in the capital.
His brother is not involved in politics, keeping a low profile as an employee in Russia's postal service company Russian Post.