Thousands of Bahrainis demonstrated near Manama on Friday urging democratic reforms, part of a series of protests planned by the political opposition ahead of next week's Formula One Grand Prix.
Under the banner "Democracy is our right," the crowds marched in the Shiite area of Aali south of the capital, waving Bahraini flags and chanting anti-monarchy slogans.
Bahrain's mainly-Shiite opposition organised the protest as part of demonstrations due to take place from April 12-22 to coincide with the April 19-22 Grand Prix.
Sheikh Ali Salman, head of the main Shiite opposition grouping Al-Wefaq who was at the protest, said the action was intended to support "demands for democratic transition".
"We do not want to hold up the race, but we are trying to benefit from the increased media presence," he said.
Salman called on his supporters to attend a demonstration planned for April 19, as the event kicks off on the Sakhir circuit south of the capital.
A second opposition group, the February 14 Movement, organised another protest on Thursday night in the village of Khamis that was broken up by police.
Thursday night's demonstration came as a report by Human Rights Watch that police have been rounding up pro-democracy activists in bid to head off protests stoked renewed controversy over the Gulf state's hosting of the Formula One event.
"Your race is a crime," the protesters chanted, referring to motor racing bosses who have insisted on keeping the Bahrain Grand Prix on the Formula One calendar, witnesses said.
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"Down with Hamad," they shouted in reference to the king, who heads a Sunni minority regime in the Shiite-majority island state.
"The people want the fall of the regime," the demonstrators chanted, echoing the rallying cry of the Arab Spring revolts in 2011.
Clashes erupted when anti-riot police intervened to disperse the crowd and demonstrators responded with Molotov cocktails, witnesses said.
One policeman was injured, when he was hit by an improvised bomb detonated remotely, the interior ministry said on Twitter.
Bahrain was rocked by month-long pro-democracy protests led by the kingdom's Shiite majority in early 2011 that were crushed with the help of Saudi-led troops.
Protests have continued in Shiite villages outside the capital. Human rights groups say a total of 80 people have been killed since February 2011.
Last year's Bahrain Grand Prix went ahead against an ugly backdrop as police responded to protesters who were throwing petrol bombs by using tear gas, sound bombs and birdshot.
Former world champion Damon Hill has called on International Motoring Federation (FIA) president Jean Todt to take an ethical stance on the controversial event.
"I think Jean's approach is say nothing because otherwise you are being political," said Hill, who won the world title in 1996.
"I think that is a mistake because actually he is being political because he's being used, or the sport is perceived as being used, by its engagement in the economy and the reputation of the country."