Russian riot police used clubs to break up an anti-Putin demonstration Sunday outside the Hermitage Museum in St. Petersburg, President Vladimir Putin's hometown.

Opposition groups said police arrested 200 people, including likely opposition presidential candidate Boris Nemtsov. The crowd chanted "Russia without Putin" as police pushed Nemtsov into a van. He was released about two hours later.

Protesters marched in St. Petersburg one day after police in Moscow arrested opposition leader Garry Kasparov, the former world chess champion, at a protest march in Moscow. Kasparov has been ordered to serve five days in jail, so he should be released just before next Sunday's parliamentary elections.

The United States says it is troubled by the detention of Kasparov and other opposition members, and particularly concerned about the aggressive tactics Russian authorities have used to crack down on protesters.

The Other Russia, an opposition coalition including Nemtsov, Kasparov and their supporters, plus other groups, organized both Sunday's protest in St. Petersburg and the rally and march in Moscow on Saturday.

During the final days before the parliamentary elections on December 2, Russia's opposition groups are trying to get wider attention for their accusations against Mr. Putin and his government. Opposition activists contend the Kremlin is trying to hijack the vote by stifling democracy and ignoring Russia's constitution.

President Putin will head his United Russia Party's candidates list on next week's ballot, and he has indicated that he might want to become prime minister. The constitution bars the president from running in March for a third consecutive term as head of state, but Russian political analysts expect him to play a powerful and influential role over the next four years, and possibly to run for president again in 2012.

Some information for this report was provided by AFP, AP and Reuters.