Pro-war blogger and President Vladimir Putin's hardline critic, Igor Girkin, who earlier criticised Russia's military strategy in Ukraine, has been remanded in custody by a court in Moscow, media reports said.
The hardline nationalist, also known as Igor Strelkov, could face up to five years in jail, reports BBC.
His wife claimed he was detained from his flat on Friday.
A former FSB intelligence colonel, Strelkov played a key role in Russia's 2014 land grab of Crimea, reports BBC.
Igor Girkin had even led Russia's proxy army in the ensuing war in eastern Ukraine.
Igor Strelkov was one of three men convicted in absentia by a Dutch court last November of murder for his role in a missile strike in 2014 that downed a Malaysia Airlines passenger jet over the conflict area, with the loss of all 298 people on board, the British media reported.
But as the full-scale invasion of last year became increasingly bogged down, Strelkov's criticism of military failings and the commander in chief, President Vladimir Putin, became more vociferous.
"We have already lost," he told social media followers last year as quoted by BBC.
A few days ago he called the Kremlin leader "a nonentity" and "a cowardly waste of space", says BBC Russia editor Steve Rosenberg.
Meanwhile, Russia’s bombardment of Ukrainian ports along the Black Sea could have far-reaching impacts on global food security, UN political affairs chief Rosemary DiCarlo said on Friday in a briefing to the Security Council.
DiCarlo strongly condemned the aerial strikes this week on the ports in Odesa, Chornomorsk and Mykolaiv, which destroyed critical infrastructure and killed or injured civilians.
The attacks followed Russia's decision on Monday to effectively end the Black Sea Initiative, the UN-brokered accord that facilitated Ukrainian grain and foodstuffs to be shipped to international markets at a time of spiralling global food prices and rising hunger.
DiCarlo said these events are but the latest developments in Russia’s "senseless war against its neighbour", which has consequences that can be felt around the world.
