Bahraini riot police have killed a teenager when they fired shotgun pellets during clashes with protesters in the country's capital, Manama, on Friday, the country's opposition said.
The teenager is the second young protester to die in Bahrain in six weeks.
Thousands rallied on Friday in an officially authorised protest called by the main opposition group al-Wefaq, but as the event ended around 100 demonstrators clashed with police.
Witnesses said riot police used tear gas and stun grenades to disperse those demonstrators, who, the authorities said, were throwing petrol bombs and wielding iron bars.
The police described the incident after the protest as a "terrorist attack" on a security patrol that "targeted the lives
of members of the patrol" late on Friday evening.
The police had defended themselves "according to their legal authority", a statement said on Saturday, confirming one of the protesters had died.
Bahrain, headquarters of the US Navy's Fifth Fleet, has been in turmoil since mass demonstrations started at the height
of Arab Spring unrest last year, led by its Shia Muslim majority.
The protests were put down by the Sunni monarchy which imposed martial law and invited Saudi Arabia to send troops in
In mid-August, a 16-year-old protester was killed in a similar incident, when police opened fire with birdshot during clashes after a demonstration, opposition activists said.
The opposition says more than 45 people have been killed in protests since martial law was lifted in June 2011. The Interior Ministry says protesters have injured more than 700 police officers and that the authorities have exercised restraint.
Al-Wefaq named the dead protester as 17-year-old Ali Hussain Nima and distributed photographs showing a body covered in blood and flecked with birdshot wounds. The pictures could not be independently verified.
Bahrain and Saudi Arabia accuse Iran of fomenting the unrest in the island kingdom and among Saudi Arabia's Shia Muslim minority, who mostly live in a province situated next to Bahrain. Iran denies the accusations.
The death comes a day after the UN Human Rights Council appointed a Bahraini as the Asia representative to its advisory committee.