Russian authorities on Thursday sentenced prominent reporter and activist Ilya Azar to 15 days in prison and detained several journalists who rallied in his support.
Azar's arrest sparked outrage among his allies and rights activists who said it was dangerous to keep the journalist in jail for two weeks during the coronavirus epidemic.
Azar, a 35-year-old municipal deputy and journalist at the award-winning independent newspaper Novaya Gazeta, was jailed for repeat violations of a protest law.
Eight journalists who gathered to picket the Moscow police headquarters in solidarity with Azar were also detained. Most were later released.
Among them were TV reporter Mikhail Fishman and journalists from Echo of Moscow radio station.
Several of the detained journalists posted pictures of themselves sitting inside police vehicles and wearing masks.
A similar number of protesters were detained in the second city of Saint Petersburg.
Azar was arrested this week during a demonstration in support of activist Vladimir Vorontsov, who has worked to expose violations within Russia's law enforcement agencies.
Vorontsov, a former policeman, was arrested in early May on extortion charges. He was later accused of also illegally distributing pornography.
Vorontsov has denied the charges, saying police are seeking to punish him for his activism.
Police said the journalists had been detained for violating a ban on rallies during Moscow's city-wide quarantine to slow the spread of coronavirus.
Amnesty International said Russia should stop using the coronavirus epidemic as a pretext to muzzle activists.
"Not only has Ilya Azar been arrested simply for exercising his right to peaceful assembly, but he has been thrown into a crowded cell where he, and others like him, are at risk of contracting COVID-19," said Natalia Zviagina, the watchdog's Russia director.
"#COVID19 cannot be an excuse to clamp down on #FreedomOfExpression," tweeted Dunja Mijatovic, the Council of Europe's Human Rights Commissioner.
Alexei Venediktov, chief editor of Echo of Moscow radio, said the arrests of Azar's supporters were an attempt to intimidate the media.
Russia has the world's third-largest number of confirmed coronavirus cases at 379,051, after the United States and Brazil.
Russia has cracked down hard on opposition demonstrations, and the single-person protest is the only kind allowed without prior permission from the authorities.
Last summer Azar helped organise a series of anti-government rallies in Moscow demanding fair elections which drew tens of thousands of people.
Police officers detained Russian photographer Victoria Ivleva in Moscow on Thursday during a solo picket in support of journalist and activist Ilya Azar
Ilya Azar, in a file photo taken in September 2019