Russian opposition leader Alexei Navalny, who is gearing up to run for the presidency, is ineligible to stand for office, the country's central electoral commission announced Friday.
A firebrand speaker and anti-corruption campaigner with a savvy grasp of social networks, Navalny declared his intention last December to stand for president. He is already mounting a campaign to gain public support for a bid.
"Currently Alexei Navalny is not eligible to stand for office," the commission said in a statement, noting that he is serving a five-year suspended sentence for embezzlement, which falls into the category of a serious crime.
Someone who is convicted of such a serious crime cannot stand for public office until 10 years after their sentence ends, the panel said.
President Vladimir Putin is expected to stand for a fourth Kremlin term in the March 2018 election, but has yet to confirm this. The nomination of candidates will begin this December.
The head of the electoral commission Ella Pamfilova earlier this month told the independent channel TV Rain that it would take a legal "miracle" for Navalny to be able to stand.
Navalny and his erstwhile business partner were convicted of embezzlement in 2013.
Navalny was given a five-year sentence that was swiftly reduced to a suspended one.
The case, which Navalny and his supporters condemn as politically motivated, has seen a number of reversals.
The European Court of Human Rights last year quashed the verdict, saying the men did not have a fair trial.
But the same Russian court held a retrial this year, issuing the same sentence. A regional court then upheld the sentence.
Navalny's lawyer Vadim Kobzev said in May that the defence team would submit a fresh complaint to the European Court of Human Rights.
The electoral commission weighed in as Navalny is already opening campaign offices across Russia to register supporters.
A presidential bid would require him to muster 300,000 signatures in the space of 40 days this winter to enter the race.
The electoral commission noted Friday that the presidential race has not yet begun, so Navalny's current campaigning activities do not fall under any electoral laws.
His campaign has seen an attacker fling green dye at his face, causing eye damage, while the Moscow campaign's rented office had its electricity switched off days after its launch.
Navalny's video alleging that Prime Minister Dmitry Medvedev is involved in shadowy corruption schemes has been viewed more than 23 million times on YouTube.
His message, delivered through social media and video blogs, has struck a chord with young Russians, who are turning out at his protests in increasingly large numbers.
Nevertheless his past support for nationalist politicians and speaking at rallies frequented by neo-Nazis troubles more traditional liberals.
Navalny is currently serving a 25-day sentence in police cells as the organiser of an unauthorised protest after he called anti-corruption demonstrations on June 12 that saw more than 1,700 people detained nationwide.
The 41-year-old lawyer has long argued that he is eligible to stand for election as he is serving a suspended sentence and is not a prisoner.
In a legal confusion he hopes to exploit, the Russian constitution says anyone who is not in prison can stand for election.
His Moscow campaign chief Nikolai Lyaskin told AFP on Friday: "The constitution does not bar Alexei Navalny from participating in elections. The central electoral commission, with its statement, is trying to break the momentum of the campaign."
"According to the constitution, any citizen who is not in prison is eligible to stand for public office."
Navalny stood for Moscow mayor in 2013, coming second against a Kremlin-backed incumbent with a Western-style campaign and a message of snuffing out corruption.
Navalny was allowed to compete in that race as he was appealing his first 2013 conviction.