A car bomb attack has wounded four Bahraini policemen in a Shia Muslim village near the capital, Manama, the authorities in the Sunni-ruled kingdom have said.
Bahrain has been rocked by sporadic violence since its security forces crushed a month of massive Arab Spring-inspired democracy protests by its Shias in 2011.
In the latest unrest, assailants remotely detonated a bomb as a police patrol passed by the car in which it had been planted in the village of Sahla on Thursday night, said the interior ministry on Friday.
"Four policemen were slightly wounded" in the explosion, said the ministry, adding that an investigation had been launched to find the perpetrators of the "terrorist act".
Clashes erupted in Shia-populated villages around Manama on Thursday evening when riot police intervened to disperse demonstrations called by the opposition February 14 Coalition youth group, witnesses said.
The protesters hurled firebombs and stones at the security forces, who responded by firing tear gas and stun grenades.
The latest unrest came two days after the resumption of a national dialogue aimed at ending the Gulf monarchy's political deadlock, following a two-month summer break.
On August 17, five police officers were wounded when an explosive device went off during clashes with opposition protesters in the Shia village of Dair, north of Manama.
Bahrain, a strategic archipelago just across the Gulf from Iran, is the home base of the US Fifth Fleet and Washington is a longstanding ally of the ruling Al-Khalifa dynasty.
At least 80 people have been killed in Bahrain since the pro-democracy protests erupted more than two years ago, according to the International Federation for Human Rights.