Highlights:
• NEW: Chess champion freed after brief detention at protest
• NEW: Kasparov's mother calls legal hearing "a shame"
• Protesters demonstrate against loss of rights under Putin
• Reports of those detained range from 170 to 600
MOSCOW, Russia (AP) -- Russian riot police beat and detained protesters as thousands defied an official ban and attempted to stage a rally Saturday against President Vladimir Putin's government, which opponents accuse of rolling back freedoms.
Authorities also have banned a similar march planned for Sunday in St. Petersburg.
A coalition of opposition groups organized the "Dissenters March" to protest the economic and social policies of Putin as well as a series of Kremlin actions that critics say has stripped Russians of many political rights.
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Kasparov seized