Security forces in Bahrain have fired tear gas and stun grenade after opposition groups staged a rare march into the center of the capital Manama.
Police set up checkpoints and many shops were closed after the Wednesday unrest. Clashes occur almost daily in the island kingdom, but mostly in areas outside the Manama's business districts.
Bahrain's majority Shiites began protests nearly a year ago to seek greater rights from the ruling Sunni monarchy.
A government statement also said at least 41 policemen were injured in clashes with demonstrators that took place elsewhere on Tuesday. One policeman has severe burns from a petrol bomb.