Riot police in Moscow clashed with about 3,500 protesters who took to the streets after authorities barred dozens of opposition candidates from upcoming local elections in the Russian capital.

Cops arrested more than 800 at the demonstration, which was called by Alexei Navalny, a jailed opposition activist and a leading critic of Russian premier Vladimir Putin, according to TV Rain, an independent news channel on YouTube.

This after electoral commission authorities banned 30 candidates from participating in elections called for Sept. 8.

Officials said that the candidates failed to collect the requisite 5,000 signatures on petitions allowing them to run for local office.

The candidates argued that the measures were too stringent since signing any petition supporting a Putin opponent puts citizens at risk of arrest.

Local police claimed only 174 were arrested.