Tens of thousands of Russians staged what a monitoring group called the country’s biggest political protest for eight years on Saturday, defying a crackdown to demand free elections to Moscow’s city legislature.

Police rounded up scores of people after the demonstration in Moscow and at another rally in St Petersburg, and detained a leading Opposition figure before it began.

But the response from the authorities was milder than the previous week when more than 1,000 protesters were detained.

The White Counter monitoring group said up to 60,000 people had attended the Moscow rally, describing it as the biggest in Russia for eight years. Police put turnout at 20,000.

A month of demonstrations over elections for the Moscow city legislature have turned into the biggest sustained protest movement in Russia since 2011-2013, when protesters took to the streets against perceived poll fraud.

Crowds at the rally in Moscow roared “down with the tsar!” and waved Russian flags. They are demanding that Opposition-minded candidates be permitted to run in a city election next month after they were not allowed onto the ballot.

“The authorities have become brazen. It’s time to defend our rights,” said Natalya Plokhova, a recruiting consultant.

President Vladimir Putin and the Kremlin have so far avoided comment.

OVD-Info, a monitoring body, said 245 people were arrested at Saturday’s demonstration in Moscow and 80 in St Petersburg. A small number of other arrests took place in other cities.

The Moscow protest was held with official permission, unlike last week’s demonstration. Afterwards, hundreds of mostly young people chanting “Putin is a thief” began gathering near the presidential administration building, prompting masked riot police to ring off the area and detain dozens.

Authorities had earlier warned protesters not to continue protesting after the officially authorised event.

Until that point the rally had passed without any major incident.

Ahead of the rally, police detained hunger-striking Opposition activist Lyubov Sobol.

“I won’t make it to the protest. But you know what to do without me....Russia will be free!” Sobol wrote on Twitter. Sobol was released late on Saturday.

Kremlin critic Alexei Navalny and at least seven allies are in jail for breaking protest law. Investigators have opened a money-laundering probe into Navalny’s anti-corruption foundation.

The focus of protesters’ anger is a prohibition on Opposition-minded candidates, some of whom are allies of Navalny, from taking part in a September election for Moscow’s city legislature.

That vote is seen as a dry run for a national parliamentary election in 2021.