Five Bahraini policemen were injured in clashes with protesters late Friday at a memorial service in a Manama suburb held for a young demonstrator who died in custody, a government statement said.
Bahraini Shiite rights activist Nabeel Rajab, meanwhile, went on hunger strike from Friday, a rights group said, just two days after he was briefly released from jail to attend his mother's funeral.
The Bahraini government said five policemen were injured and "several rioters" were arrested during protests that turned violent late Friday.
The clashes followed a confrontation that erupted at a memorial service held in the Manama suburb of Jad Hafs for a young Bahraini who died in custody Tuesday.
The Bahraini was jailed for his participation in the February 2011 anti-government uprising and died in custody after he was hospitalised for treatment of a hereditary disease.
"After the funeral ritual in Jad Hafs for Mohammed Mushaima who died from complication from sickle cell disease, a large number of people formed an illegal rally," the government said.
It said the protesters "blocked traffic and attacked policemen with petrol bombs, iron rods and rocks ... five policemen sustained injuries and a police jeep was gutted by fire."
The government statement said that "legal procedures were taken to arrest (the rioters)." It did not specify how many people were arrested.
Witnesses at the scene said riot police, who were heavily deployed in the area, used tear gas, water cannon, sound bombs and buckshot to disperse the demonstrators.
Meanwhile, Rajab, 48, who is serving a three-year sentence for participating in illegal demonstrations, went on hunger strike after he was allowed out of jail for a day to bury his mother but barred from attending a three-day condolence gathering.
"In protest against this unjustified punishment, (Rajab) started a full hunger strike (on Friday)," said the Bahrain Centre for Human Rights (BCHR).
Bahraini authorities say Rajab was barred from attending the condolence gathering because he "delivered a speech inciting mourners to stage illegal protests" when he was briefly released to attend the funeral.
"Because of his actions, Rajab has had the privilege to attend further mourning gatherings revoked," the authorities said.
The BCHR said that Rajab called on mourners to "continue their struggle for rights and democracy," and argued his speech was a "peaceful expression of opinion."
The courts have merged Rajab's three separate cases of "incitement and illegal assembly" into one single appeal.
Rajab led anti-government protests following a crackdown on Shiite-led demonstrations against the Sunni Al-Khalifa regime in March 2011.