Russian investigators on Monday opened a third criminal case against an opposition leader who poses one of the main challenges to President Vladimir Putin in opinion polls.
The Investigative Committee said it had charged the anti-corruption blogger and lawyer Alexei Navalny with "swindling committed by an organised group or on an especially large scale".
The offence carries a jail sentence of up to 10 years.
Navalny spearheaded the opposition movement that emerged last winter in the wake of disputed parliamentary elections that the ruling party won despite suspicions of fraud.
The 36-year-old Navalny -- often ranked as the most popular opposition campaigner and an emerging politician who has not ruled out running for president -- denies all the charges and views the probes against him as political.
"Lord, they have opened another criminal case against me," Navalny tweeted moments after the news was announced. "The Investigative Committee -- what are you doing... Enough already."
Navalny is already the focus of an embezzlement probe linked to a murky business deal conducted by a small regional timber company in which he was involved. That offence also risks a 10-year sentence.
Investigators last week also launched a money laundering investigation against Navalny and his brother related to a little-known trading company.
The latest case involves 100 million rubles ($3.2 million at current exchange rates) allegedly stolen from a liberal political party called the Union of Rightist Forces (SPS) in 2007.
The charges state that a company involving Navalny had secured an SPS advertising contract that was never properly fulfilled.
Navalny's Allekt firm "transferred the money it received on accounts of firms, most of which bore the signs of fake enterprises and fly-by-night operations," the committee said in a statement.
SPS disbanded in 2008 after badly losing a series of elections and none of its former leaders issued an immediate comment.