Igor Girkin, a prominent Russian nationalist and vocal critic of President Vladimir Putin, was taken into custody on Friday on charges of inciting extremism.
His arrest earlier in the day by his former employer, the FSB state security service, suggests authorities have wearied of his criticism of what they call Russia's “special military operation”.
It follows an abortive mutiny last month led by another outspoken critic, Yevgeny Prigozhin, head of the Wagner Group mercenary force, who is still free but has sharply curtailed his own verbal attacks.
The charge brought by FSB prosecutors carries a maximum sentence of five years in prison, state news agencies Tass and Ria Novosti reported.
The RBC news site said the Meshchansky district court in Moscow had ordered Girkin, 52, be detained in investigative custody until September 18.
Girkin, a former FSB officer and battlefield commander also known as Igor Strelkov, helped Russia to annex Crimea in 2014 and, soon after, to organise pro-Russian militias.
He was also handed a life sentence in absentia by a Dutch court in 2022 for his alleged role in the shooting down of Malaysia Airlines flight MH17 over eastern Ukraine in 2014, with the loss of 298 passengers and crew.
In footage from court posted by the popular Telegram channel Shot, Girkin stood almost motionless in a glass cage, with his arms folded, staring straight ahead.
He had been regarded by many as untouchable due to his history and ties to the establishment, but had become more outspoken in recent months.
Girkin announced in May that he and others had set up the “Club of Angry Patriots” to save Russia.
Asked at the time if he was naive to launch a political movement without the assent of the Kremlin, he said: “I hope you would not call me a naive person.”
In one of his most outspoken tirades, in a post on July 18 on his official Telegram channel – followed by more than 760,000 people – Girkin peppered Mr Putin with personal insults and urged him to pass power “to someone truly capable and responsible”.
RBC, citing two unnamed law enforcement sources, said Girkin's Moscow home had been searched.
Tatiana Stanovaya, founder of the R.Politik analysis firm, said the men who run Russia's law enforcement and power ministries had long wanted to arrest Girkin.
“Strelkov [Girkin] had overstepped all conceivable boundaries a long time ago,” she said. “This is a direct outcome of Prigozhin's mutiny: the army's command now wields greater political leverage to quash its opponents in the public sphere.”
Ms Stanovaya said Girkin's detention was a signal that any of the bitterest critics of Moscow's approach to the war could face prosecution
