Russian prosecutors on Monday accused protest leader Alexei Navalny of breaking the law by receiving donations from abroad for his campaign as Moscow mayor.
Navalny, 37, a fearless critic of President Vladimir Putin, is standing for Moscow mayor with a campaign to root out corruption despite being convicted last month of embezzlement, in a widely disputed verdict.
"A check has confirmed information about foreign financing of Alexei Navalny," the prosecutor general's office said in a statement published on its website.
It alleged that more than 300 named foreign donors and also anonymous donors from 46 countries gave money to Navalny and his campaign chiefs using a Russia-based Internet payment system.
Prosecutors said they handed the information to the interior ministry for it to decide whether to open a criminal case.
Prosecutors launched the probe at the request of nationalist politician Vladimir Zhirinovsky, whose party has a candidate standing in the race.
Navalny's team denied the claim. Campaign organiser Vladimir Ashurkov told the RIA Novosti news agency that donations for Navalny's campaign fund could only be made by Russian nationals.
Navalny, a charismatic lawyer, faces a five-year jail term after being convicted of embezzlement in a timber deal last month. He was freed from prison the next day in a surprise decision to allow him to stand in the mayoral race.
Kremlin-appointed incumbent Sergei Sobyanin is expected to win a new term as Moscow mayor, controlling a city budget of more than $50 billion in the September 8 polls.
Sobyanin has refused to take part in televised debates with the other candidates, the first of which is due to be held Monday evening.