Navalny, Russia's highest profile critic of Vladimir Putin, was given a nine-year jail sentence earlier this year.
Russian opposition leader Alexei Navalny has had his appeal rejected by a Russian court over a decision to label him an extremist and a terrorist.
Russian President Vladimir Putin's main critic took part in the proceedings via video link on Tuesday.
The 46-year-old argued that the decision to be put him on this list was unlawful.
"I definitely stand behind every word of the appeal," said Navalny. "I believe I was put on that register illegally both procedurally and by definition and of course, it's the definition that bothers me the most. I don't understand why I was labelled not only an extremist but a terrorist."
Navalny was arrested in January 2021 when he returned from Germany where he'd been recovering from nerve-agent poisoning. He was handed a two-and-a-half-year sentence for a parole violation.
Then in March this year, he was sentenced to nine years in prison on fraud and contempt of court charges which he calls a politically motivated move.
Watch Euronews's report in the player above.