Thousands of people took to the streets of Khabarovsk, in Russia's far east, on Saturday, in the tenth consecutive protest since the arrest of the region's former governor.
Observers said some 9,000 people protested, carrying flags and posters, while city officials put the number at 700.
The demonstrators called "Russia, stand up," "Freedom for political prisoners" and "We are Sergei Furgal."
Former governor Sergei Furgal was arrested on 9 July and is on remand in Moscow. Investigators accuse him of having commissioned two murders when he was a businessman 15 years ago. In another case he is accused of attempted murder.
The 50-year-old denies the allegations, saying they are politically motivated. He defeated the Kremlin's approved party candidate in the 2018 gubernatorial election.
The protests come as Russians vote in regional elections for new governors and lawmakers this weekend, also in Khabarovsk.
The organizers of Saturday's rally applied for a permit for the first time, since protests were previously banned due to virus restrictions that were lifted at the start of the month. Their application was denied, however.
Police have detained 23 people since mid-July when the protests began, and are investigating 175 people for taking part in the demonstrations.
Although the rallies in Khabarovsk have drawn thousands of attendees, police have not broken up the events, and have detained relatively few people compared to unauthorized demonstrations in Moscow.
Khabarovsk, near Russia's Pacific coast, is some 6,000 kilometres from Moscow, the capital.