Tens of thousands of demonstrators turned out in Moscow Saturday to protest the refusal of authorities to allow a slate of independent candidates on the fall city council elections ballot.

Unlike last Saturday's demonstration in front of Moscow city hall, this weekend's rally at Andrei Sakharov Square was authorized, although many people had to wait in long lines to go through security to reach the site.

A group that monitors attendance of public meetings, Beliye Schetchik, said it counted about 50,000 people at the demonstration; a police estimate put the crowd at 20,000.

After the authorized rally, which featured speakers and entertainers, hundreds of protesters headed for the presidential administration building for more demonstrations. Some among the crowd shouted "Putin is a thief," according to Reuters.

Heavily armed police, who sealed off the high-profile area, detained 136 people, according to the arrest-monitoring group OVD-Info.

In St. Petersburg, 70 people were reported arrested at an unsanctioned demonstration mounted in support of the Moscow rally..

At the Moscow event, OVD-Info said 10 people were detained, although it was not immediately clear on what grounds.

In a sign of growing support for the protests, two young Russians with millions of followers on social media -— YouTuber Yury Dud and rapper Oxxxymiron — called on their supporters to join Saturday's authorized rally.

Three popular Russian musical acts — IC3PEAK, Krovostok and Face — performed for some 50,000 people who gathered in the square in front of a stage.

“I had to perform today to show my support,” Anton Chernyak, the lead singer of Krovostok, told The Moscow Times. “It’s great so many people turned up.”

At least one of the would-be candidates, Lyubov Sobol, who is on a hunger strike, was detained by police before the rally, according to the independent newspaper Moscow Times.

Sobol posted a video on Twitter of the moment when police broke into her office to take her into custody.

In addition to Moscow's rally, which was livestreamed by the independent Dozhd TV, similar solidarity protests were held in other Russians cities, according to jailed protest leader Alexei Navalny. These include St. Petersburg, Vladivostok, Yekaterinburg, Tyumen,, Krasnodar and Rostov-on-Don.

At issue is access to the fall ballot for the 45-seat Moscow City Council. The opposition-backed candidates have been rejected by authorities who claim they did not get enough signatures to qualify. The candidates reject this claim.

Russia's main election board this week rejected their appeals, including one by Sobol.

Contributing: Associated Press