A Moscow court Wednesday ordered one of the last prominent opposition figures still in Russia, Ilya Yashin, to be detained for two months before trial for having denounced Moscow's Ukraine offensive.
The judge ruled to leave Yashin behind bars until September 12.
If convicted, he faces up to a decade in prison for spreading "false information" on Russian forces fighting in Ukraine.
"Do not be afraid of these scoundrels! Russia will be free!" Yashin shouted in court.
Around 40 people came to support Yashin, a Moscow city councillor, outside the capital's Basmanny district court.
He was charged with "discrediting" the Russian army on Tuesday evening, as he was due to be released from 15 days in detention for disobeying police.
The 39-year-old refused to leave Russia after President Vladimir Putin sent troops to Ukraine in February and has since then regularly denounced the move.
Almost all of Putin's well-known political opponents have either fled the country or are in jail.
"This is a politically motivated case from the first to the last page," Yashin said, sitting smiling in the defendant's glass box.
The bearded politician was handcuffed and wearing a khaki-coloured T-shirt.
The judge then granted a request by investigators for a closed hearing closed "for the purpose of non-disclosure of state and other secrets protected by the law."
The reason for the probe was an April YouTube stream in which Yashin spoke about the "murder of civilians in Bucha", the Kyiv suburb where Russian forces have been accused of war crimes.
He called it a "massacre".
After sending troops to Ukraine, Moscow adopted laws imposing sentences of up to 15 years for spreading information about the military deemed false by authorities.
- 'Knew would be arrested' -
Last week, another Moscow councillor -- Alexei Gorinov, also from Yashin's Krasnoselsky district -- was sentenced to seven years in prison for denouncing the Ukraine offensive.
Yashin's case is more high-profile.
He was a key figure in Moscow's mass anti-Putin protests in 2011-12 and a close associate of assassinated politician Boris Nemtsov.
Despite growing pressure on dissenting voices, Yashin vowed to stay put and seemed prepared for an arrest.
Yashin has regularly condemned the Kremlin's offensive on his YouTube channel which has 1.3 million subscribers.
"Let's be honest: since February 24 (when Putin sent troops to Ukraine), I knew perfectly well that I would be arrested," he said on Facebook after the ruling.
He said he had "kept his promise" to "keep loudly telling the truth for as long as I can".
Despite disagreeing on some issues, Yashin has expressed admiration for opposition leader Alexei Navalny, who returned to Russia from Germany after suffering a poison attack and is now serving a nine-year jail term.
Yashin was detained while strolling through a Moscow park with a friend in late June and jailed for allegedly disobeying police orders.
In late April, another opposition activist, Vladimir Kara-Murza, was first detained and later also slapped with charges of spreading "fakes" on the Russian army.
