Russian newspapers on Thursday denounced a growing police crackdown on peaceful protesters and the sentencing of a popular news editor to jail for retweeting a joke.
Over the past two weekends, tens of thousands of people have taken to the streets nationwide in support of jailed opposition politician Alexei Navalny, President Vladimir Putin's most vocal critic.
A court on Wednesday sentenced Sergei Smirnov, chief editor of Mediazona -- an online news publication often critical of the government -- to 25 days in jail over a retweet of a joke that included the time of a protest rally on January 23.
"Over the past few weeks we've witnessed extremely harsh actions of members of law enforcement," leading broadsheet Kommersant said in a statement.
"Beatings and mass detentions should not become the norm in our country."
Kommersant said Smirnov's arrest was an "attempt to intimidate" both Mediazona journalists and other reporters.
Respected business daily RBC said several of its journalists had witnessed "detentions and the use of force" against the media during the protests.
The newspaper demanded that law enforcement publicly explain the arrest of Smirnov and other journalists.
Independent monitors say at least 10,000 people have been detained at the recent demonstrations, the majority of them in Moscow.
Russia's Union of Journalists says over 100 media workers were either injured or detained at rallies.
Moscow's detention centres have been severely overcrowded following the influx of detainees serving short-term jail sentences for taking part in the demonstrations.
Smirnov is being held in a detention centre for migrants outside the Russian capital.
On Thursday, an AFP journalist saw around 100 people queueing outside the Sakharovo centre, waiting to pass care packages to the detainees.
Photos shared on social media from inside Smirnov's cell showed a crammed room, with two or three people sharing a metal cot with no mattress.
Smirnov was seen trying to sleep sitting up and leaning against the metal bar of a bunk bed. The editor said on Twitter on Thursday he was moved to a cell with fewer people and given a mattress.
Navalny's allies called on Russians to take to the streets after he was detained last month on arrival from Germany where he had been recovering from nerve agent poisoning.
On Tuesday, a court ruled that he must spend two years and eight months in prison for violating the terms of a 2014 suspended sentence on fraud charges.