Thousands of Russians filled the streets of central Moscow Saturday, calling for free elections to the city’s legislature.

The protest was the latest in a series that stem from the exclusion of some opposition and independent candidates from the Moscow City Council, Reuters reported.

The unauthorized march following recent demonstrations in which thousands were detained and many beaten by police, The Associated Press reported. Charges filed against 14 people arrested in earlier protests could send them to prison for up to eight years.

The protests, including a sanctioned one this month that attracted some 60,000 people, are the largest outburst of dissent in Russia since 2011-12.