Moscow -- Protesters once again took to the streets of Moscow Saturday, decrying the exclusion of some independent and opposition candidates for upcoming city council election that has shaken up Russia's political scene. Moscow police detained at least 600 protesters Saturday, a monitoring group said, a week after authorities arrested nearly 1,400 people at a similar protest.

Law enforcement officers detain Russian opposition politician Lyubov Sobol before a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, Russia August 3, 2019. TATYANA MAKEYEVA / REUTERS

Lyubov Sobol, one of the excluded candidates and a driving figure of the current wave of protests, was among those detained. She was grabbed by police in central Moscow and hustled into a police van, loudly demanding to know why she was being held.

Demonstrators were aiming to hold a march along the Boulevard Ring, which skirts central Moscow and is a popular locale for people to walk around, despite repeated warnings that police would take active measures against a protest.

Helmeted riot police lined the route and started seizing demonstrators from a scattered crowd on Pushkin Square and pushing them back from another square further along the route.

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Some of the detentions were harsh, including one young bicyclist who was beaten with truncheons as he lay on the pavement still straddling his bike. Some other detainees appeared nonchalant, smirking or checking their phones as police led them to buses.

Law enforcement officers detain a participant in a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, Russia August 3, 2019. SHAMIL ZHUMATOV / REUTERS

The OVD-Info group, which monitors arrests, said at least 600 people had been detained.

Once a local, low-key affair, the September vote for Moscow's city council is now emblematic of the division within Russian politics and the Kremlin's ongoing struggles with how to deal with strongly opposing views in its sprawling capital of 12.6 million people.

"They (the authorities) are wiping their feet on us," one student at Saturday's protest told Reuters.

In the past month, the issue has provoked a surprisingly large outcry for a local election. On July 20, about 20,000 people turned out for a demonstration that was the largest in the city in several years.

On Saturday, about 2,000 people attended another rally in St. Petersburg supporting the Moscow protests, the local news site Fontanka.ru reported.

The Moscow city council, which has 45 seats, is responsible for a large municipal budget and is now controlled by the pro-Kremlin United Russia party. All of its seats, which have a five-year-term, are up for grabs in the Sept. 8 vote.

Also Saturday, Russia's Investigative Committee announced it was opening a criminal case against the Foundation for Fighting Corruption, headed by the Kremlin's most prominent foe Alexei Navalny. The committee said the organization was suspected of receiving funding that had been criminally acquired.

Last week Navalny was released from a Moscow hospital after a mystery illness that his doctors say may have been the result of a poisoning. Navalny, who had been arrested and sentenced to a month of detention for calling an unauthorized protest, was taken back to prison to serve out the rest of his sentence.

Navalny had been suffering what appeared to be a severe allergic reaction. His spokeswoman Kira Yarmysh said on Twitter that the politician had severe facial swelling and a rash all over his body.