Russia's main opposition leader, Alexei Navalny, has been found guilty of embezzlement and handed a five-year suspended sentence.
It bars him from running for president next year against Vladimir Putin.
Mr Navalny accused the Kremlin of trying to block him from standing for president and vowed to take part in the race regardless. It was not immediately clear if this was legally possible.
The court, in the provincial city of Kirov, found Navalny guilty of embezzlement in relation to a timber firm called Kirovles, and gave him a five-year suspended prison sentence. Navalny denies wrongdoing.
"What we are seeing now is a sort of telegram sent from the Kremlin, saying that they believe that I, my team, and the people whose views I voice, are too dangerous to allow us to take part in the election campaign," he said.
"We don't recognise this ruling. I have every right to take part in the election according to the constitution and I will do so," he told reporters in the court room, moments after the sentence was handed down.
But the legality of his candidacy is in question, as under Russian law anyone is banned from running for office for 10 years after being convicted of a serious crime. Separately, the constitution bans anyone from running who is physically in prison.
His conviction came in a retrial after the European Court of Human Rights ruled the first trial to be unfair.
The outspoken critic of President Putin has vowed to appeal against the embezzlement verdict.
Kremlin spokesman Dmitry Peskov has dismissed concerns raised about Mr Navalny's absence undermining the legitimacy of the election.
"We believe any concerns about this are inappropriate," he said, speaking before the trial concluded.
Mr Navalny, 40, is known for his anti-corruption campaign, which targeted senior officials close to the Kremlin.
He had recently stepped up his political activity after announcing plans last year to run for the presidency in 2018. Vladimir Putin is allowed by the constitution to run for a second consecutive six-year term, but he has not said yet if he plans to do so.
Mr Navalny's rise as a force in Russian politics began in 2008 when he started blogging about alleged malpractice and corruption at some of Russia's big state-controlled corporations.
He described the president's United Russia as "the party of crooks and thieves", a phrase that appeared to resonate with many in Russia.
He stood for Moscow mayor in 2013 and got more than a quarter of the vote.
- BBC / Reuters