A demonstrator sprays graffiti during a protest in the village of Diraz, west of Manama April 21, 2012. Crowds of masked protesters hurled petrol bombs at police who fired tear gas back in Bahrain on Saturday, turning the streets into a battle zone on the eve of a Formula One Grand Prix that demonstrators say glorifies a repressive government. REUTERS/Hamad I Mohammed (BAHRAIN - Tags: POLITICS CIVIL UNREST)