Security was significantly higher along the 30-kilometer (19 mile) route from Manama to the track on Friday and numerous roads were blocked as two days of Formula One practices began.

Overnight clashes between protesters and police in Shiite Muslim villages carried on into Friday morning. Police used teargas and stun grenades to disperse activists, who responded with petrol bombs.

"The people want to topple the regime," protesters chanted, shouting "Down with Hamad," in reference to Bahrain's king.

Anti-government demonstrations also took place on Thursday in Manama, where they are banned for the three days of the Bahrain Grand Prix. Even so, activists called for three "days of rage" to start on Friday afternoon in front of the Bahrain International Circuit.

Shiite-led opposition

The government's critics say it is using the race to improve its international image.
Bahrain is ruled by a Sunni royal family, with the majority Shiite population saying they are subject to economic and political discrimination in the small, oil-rich kingdom.

Last year the Bahrain Grand Prix was first delayed and then ultimately abandoned in the wake of an uprising against the government. Amid mounting pressure, the race organizers announced at the eleventh hour that they would forego the 2011 race "so that the country can focus on its process of national dialog."

A government commission said 35 people were killed in the government crackdown. Activists say 70 people have been killed since the uprising began last spring.

ncy/rg (AFP, AP, Reuters, dpa)