Russian riot police arrested hundreds of activists in central Moscow yesterday to stop a new protest alleging that elections were rigged in favour of Vladimir Putin's ruling party.

Helmeted police in green camouflage and interior ministry troops deployed in force for an event that was organised through the internet after a rare thousands-strong protest on Monday startled the authorities.

Opposition supporters shouted 'Shame on you fascists!' and 'Russia without Putin' in a tense stand-off with hundreds of pro-Kremlin youth who descended on the site in advance.

Those detained in Moscow included former Cabinet Minister turned Kremlin critic Boris Nemtsov – released after being booked at a police station – and several other members of opposition groups that were barred from running in the polls.

A Moscow police spokesman said 250 people had been thrown into waiting vans and taken to various police stations about two hours into the event. Interfax cited a security source as saying 300 had been detained.

Police in Mr Putin's native city of Saint Petersburg also reported making around 200 arrests.