Russia's top court has upheld a decision barring opposition leader Alexei Navalny from running for president in March.
The 41-year-old lawyer announced his candidacy last week, but Russia's Central Election Commission later ruled that he could not take part in the elections due to an earlier conviction of fraud.
Navalny responded by filing an appeal, which was, however, dismissed by the Supreme Court on Saturday.
Shortly after the upholding of the ban, Navalny used Twitter to call on his supporters to boycott the March 18 vote.
A staunch critic of President Vladimir Putin, Navalny rose to prominence in Russian politics in 2008.
He was the driving force behind massive anti-Putin protests in 2011 and 2012, rallying tens of thousands of people across the country.
In 2013, he was first sentenced on embezzlement charges, after being accused of defrauding the Kirov regional budget of about $270,000.
The European Court of Human Rights last year quashed the ruling.
As a result, Russia's Supreme Court ordered a retrial.
Last February, in a retrial of the 2013 case, Kirov city court handed down a five-year suspended prison sentence and a fine of about $8,500 to Navalny.
Navalny has always maintained that the conviction was politically motivated.
Earlier this month, Putin announced that he plans to run for another six-year term.
Putin, 65, was president from 1999 until 2008. He then served as prime minister from 2008 until 2012, before becoming president again.
Polls show Putin is favoured to win the elections.
