Bahraini police fired teargas to break up a protest in a Shia district outside Manama today, during Bahrain's Formula One Grand Prix, and protesters responded with petrol bombs.

"Protesters were at a roundabout in Diraz and police tried to move them by firing teargas. They started throwing petrol bombs back at them," a Reuters witness said.

He said there were up to 150 protesters, who had taken part in a march of several thousand earlier for democratic reforms and against Formula One, and around 50 riot policemen in jeeps.

Demonstrators west of Manama took to the streets earlier in a march called by opposition parties, holding banners for democratic reforms in the Shia-majority Gulf Arab state, which is governed by the Sunni Muslim Al Khalifa family.

They held up a banner depicting Formula One race drivers as riot police beating up protesters.

A protest by more than 15,000 people nearby yesterday also ended in clashes with riot police as hundreds sought refuge from teargas in a shopping mall and youths threw petrol bombs.

Police have stepped up their presence in the area because it is adjacent to the main highway from Manama to the Formula One race circuit. Some team members have run into clashes between police and youths on the road.

The dead body of Salah Abbas Habib was found this morning after he took part in clashes with police last night in a village near the highway.

This afternoon police used teargas to stop hundreds of protesters reaching a main road in al-Bilad al-Qadeem, a Shia neighbourhood of Manama.

"They used rubber bullets, teargas and sound bombs," said Mohammed al-Maskati of the Bahrain Youth Society for Human Rights. He said he had attended the march, held in protest against the death of Mr Habib, who came from the neighbourhood.