MOSCOW (AFP) - Anti-corruption campaigner Alexei Navalny has cemented his status as leader of Russia's opposition movement by organising the largest unauthorised protest in recent years against President Vladimir Putin's rule.
The clean-cut 40-year-old lawyer, who has harnessed the power of the Internet to get his message to young and educated Russians, was arrested at Sunday's demonstration in Moscow and sentenced to 15 days behind bars for his alleged insubordination to police.
Navalny is no stranger to clashes with the Kremlin; he spent time under house arrest and saw his brother jailed in a string of cases he has denounced as retribution for challenging authorities and exposing the vast wealth of Putin's inner circle.
Last year, in his most ambitious move yet, he announced he would run for president in 2018, an election that Putin is expected to dominate.
This month Navalny posted a YouTube video tracing Prime Minister Dmitry Medvedev's links to mansions, yachts and vineyards. The clip has been viewed 12 million times.
No official response followed, and Navalny called supporters to protest across Russia. Thousands turned out in Moscow, where some 1,000 people were arrested including Navalny.
In February Navalny was found guilty in a retrial of an embezzlement case that could make him ineligible to stand for president -- though he insists he will not be forced out of the race.
Criticised by some liberals for his anti-immigrant nationalist stance, Navalny has tapped into discontent among the young urban middle class with fiery speeches and Western-style campaigning.
"I will discuss what everyone has been silent about but has needed to be said for a long time," Navalny said in December when announcing his presidential bid.
But in an environment where the Kremlin tightly controls the media and political landscape, Navalny remains a fringe figure for most Russians, who are more likely to believe the official portrayal of him as a Western stooge and convicted criminal.
"Navalny is a unique politician of the younger generation," said Nikolai Petrov, a professor at the Higher School of Economics in Moscow, adding that he had managed to develop a high profile "at a time when public politics has ceased to exist."
- Protests and payback -
During mass protests in 2011 sparked by vote rigging allegations, Navalny grabbed attention with his uncompromising rhetoric.
In front of crowds of tens of thousands, he coined catchy phrases such as the "party of crooks and thieves" to slam the governing United Russia.
Although the protests petered out after a crackdown and Putin sailed to a third term in March 2012, they helped launch Navalny's political career.
In 2013 he ran a crowd-funded campaign for mayor of Moscow and ended up finishing second.
Navalny has also faced a series of legal cases, which supporters see as a sign the Kremlin is running scared.
In 2013 he was found guilty in an embezzlement case involving an allegedly crooked timber deal and given a five-year suspended sentence which disqualified him from standing for public office.
The European Court of Human Rights threw out the verdict last year but a retrial issued Navalny the same sentence.
He then had to spend months under house arrest and was often kept incommunicado over another graft case linked to French cosmetics company Yves Rocher.
He was given another suspended sentence, and his brother Oleg, a co-defendant, was jailed for three and a half years.
- Palaces and pooches -
While barred from mainstream politics, Navalny has kept trying to expose the lavish wealth of the elites of the Putin era, broadcasting the findings of his investigations to his 1.8 million Twitter followers and to millions more on YouTube.
Trawling through land registries and the filings of offshore companies, Navalny and his team have helped lay bare the hidden fortunes of high-ranking officials.
His team produces accessible video reports with a savvy grasp of Internet memes and catchy images that are then picked up by supporters on the street.
The latest video on Medvedev focused on a garish pair of trainers worn by the premier, which prompted supporters at the Moscow protest to string shoes from lampposts.
Among Navalny's most eye-catching exposes have been details on the palatial homes of Putin's allies in Russia and abroad -- including one kitted out with a vast storage room for fur coats built by Vladimir Yakunin, former chief of Russia's national railways.
"Dear friends, those who voted for Putin and United Russia, you made it possible for Russian officials to steal completely openly and live as they do," Navalny said in an online video.
"Please don't ever do this again."