Hundreds of people attended a sanctioned rally in the Russian capital on June 23 to denounce what they called fabricated cases against activists and journalists.
Police said some 1,800 people took part in the rally on Sakharov Avenue in downtown Moscow.
The rally was initially called in support of investigative journalist Ivan Golunov, who had been briefly arrested this month on a drug charge supporters said was fabricated.
Golunov was released amid public outcry on June 11. Protest organizers have said that many other activists are still behind bars on fabricated charges.
A reporter for the Latvia-based Russian online news site Meduza, Golunov specialized in investigating corruption among top Moscow city officials and others.
Golunov, his colleagues, and supporters rejected the drug charge against him, calling it absurd and contending that he was being punished for his reporting.
Golunov's arrest on June 6 outraged many Russian journalists and human rights activists. The case added to public anger over what many Russians see as arbitrary and unjust actions by state officials and others with influence who critics say serve their own interests rather than those of the people.
On June 12, several hundred people marched through central Moscow in an unsanctioned protest aimed at maintaining pressure on authorities over Golunov's case.
The OVD-Info, an independent group that monitors police crackdowns against demonstrations in Russia, says at least 513 demonstrators were detained in that rally.
With reporting by TASS