Bahraini security forces chased youths in a Shi'ite town on Wednesday and one man was killed when his car was hit by a police vehicle, activists said, hours before the release of a report on the sectarian strife that has roiled the kingdom.
Witnesses said riot police in 4x4 vehicles sped through the streets of Aali, outside the capital Manama, in pursuit of dozens of teenagers, before seizing one and beating him with batons as helicopters circled overhead.
Graffiti in the area read "Death to Al Khalifa", a reference to the Sunni ruling family, which Bahrain's majority Shi'ites accuse of denying them access to housing, land and state employment on sectarian grounds.
Security forces used tear gas to scatter dozens of people who marched through the centre of the town chanting "Down with Hamad", the monarch Hamad bin Isa al-Khalifa. Acrid black smoke rose from burning tyres.
Hours earlier, a security forces vehicle in the town smashed into the car of Abdelnabi Kadhim Aaqil, which struck a parked vehicle and killed the driver, activists said. Security forces fired tear gas and rubber bullets after the crash, they said.
It was not clear whether the dead motorist had been involved in protests, which take place almost daily in Shi'ite regions of Bahrain and are often put down by security forces with tear gas.
The dead man's home, reeking of tear gas, was deserted and apparently abandoned by its occupants, after what neighbours said was a raid by security forces that is typical of their reaction to protest-related deaths in the area.
"They behave savagely," said a 32-year-old resident of the neighbourhood who identified himself as Hussein. "They want no voice raised against them ... the idea is to frighten us."
Elsewhere in Aali, graffiti read "Your turn is coming," an apparent reference to the toppling of Arab leaders in Tunisia and Egypt after mass demonstrations.
In its Twitter feed, Bahrain's Interior Ministry called the incident in Aali a traffic accident and said it had completed a forensic investigation, but gave no details.
The violence came hours before the release of a report commissioned by Bahrain into the anti-government protests earlier this year, led by Shi'ites, and the subsequent crackdown featuring mass arrests and allegations of torture.
Bahrain called in Saudi and UAE troops in mid-March to help crush the protests, which it says Iran fomented through its co-religionists on the island. Bahrain hosts the US Navy's Fifth Fleet and is financially dependent on Saudi Arabia.
Rights groups and activists estimate more than 3,000 people were detained in the crackdown and say as many as half of them suffered abuse, including electric shocks and beatings.
Bahrain commissioned jurists led by Egyptian-American international law expert Cherif Bassiouni to report on the unrest, the worst since sectarian-tinged political violence rocked Bahrain in the mid-1990s.
The United States has said a $53 million arms deal depends on the report, and Bahrain has already admitted security forces used excessive force in some cases, while denying any coordinated policy of torture.
The report follows a state-orchestrated "national dialogue" about the unrest which opposition groups dismissed as a farce.