The authorities have opened another criminal investigation against the opposition leader Alexei Navalny on suspicion of fraud and money laundering.
Mr Navalny, an anti-corruption blogger who has organised protests in the past 12 months against President Vladimir Putin, already faces charges of theft which he says are politically motivated and part of a Kremlin clampdown on dissidents.
The federal investigative committee said on its website that Mr Navalny and his brother were being investigated over the alleged theft of 55m roubles (£1.1m) by a trading company they are involved in.
The latest investigation was announced on the eve of an opposition march against Mr Putin planned for today in Moscow.
Mr Navalny was not available for comment. He has denied the earlier charges, over the alleged theft of timber from a state company.