Russia's anti-Kremlin opposition said it was planning a nationwide protest next weekend despite police forcibly detaining over 1,000 people on Saturday for attending what they said was an illegal march in Moscow to demand free elections.

Saturday's protest, conceived by opposition activists as a peaceful walk to protest the exclusion of their candidates from a Moscow election next month, was systematically and sometimes violently dispersed by police.

OVD-Info, an independent monitoring group, said on Sunday that police detained 1,001 people on Saturday, up from its earlier estimate of just over 800 people. Many but not all of those detained were later released by police, but OVD-Info said 19 were kept in custody overnight.