Navalny, who called a World War II veteran and other people featured in a pro-Kremlin video last year as “corrupt stooges” and “traitors, has rejected the slander charges and described them as part of official efforts to disparage him.
A Moscow court has convicted top Kremlin critic Alexey Navalny of defamation, just hours after another court upheld an order for him to serve more than two years in prison in another case.
Judge Vera Akimova said Navalny was guilty of defaming a World War II veteran who was among a group of Russians Navalny called "traitors" for appearing in a pro-Kremlin video.
Navalny was fined around $11,000 (850,000 roubles) and prosecutors want his 2014 sentence turned into real jail time because the alleged defamation took place while he was serving the suspended term.
Before the judge began reading the verdict Navalny made jokes and spoke to reporters from inside his glass box.
"Why are you so sad?" he said, adding he was trying to make ice cream in jail and had already made pickled cucumbers.
Earlier Saturday another court upheld a ruling to jail 44-year-old Navalny, sealing his first lengthy prison sentence after a decade of legal battles with Russian authorities.
A Moscow appeal court upheld a prison sentence imposed on Navalny after he returned to Russia from Germany last month.
Judge Dmitry Balashov rejected Navalny's appeal of the February 2 ruling, which turned a 2014 suspended sentence on embezzlement charges into real jail time.
The judge decided to count six weeks Navalny was under house arrest as part of the time served, so he will now be imprisoned for just over two-and-a-half years in a penal colony.
Navalny, who has emerged as President Vladimir Putin's most prominent opponent, was arrested in January when he returned to Russia after months in Germany recovering from a nerve agent poisoning he blames on the Kremlin.
He was detained for violating parole conditions of the 2014 suspended sentence and it was then turned into a custodial sentence.
Navalny and his supporters say the rulings and several other cases against him are a pretext to silence his corruption exposes and quash his political ambitions.