Protesters have clashed with police in the Bahraini capital, Manama, after their march was stopped from proceeding towards Pearl roundabout, the focus of the mass protests that began in February last year.
Police used water cannon and tear gas to disperse hundreds of protesters on Friday after a memorial for a Shia man jailed over last year's pro-democracy uprising, witnesses have said.
The interior ministry said on Twitter that a "group of terrorists" attacked police with Molotov cocktails and blocked streets, prompting police to take "legal measures" in response.
Witnesses said riot police, who were heavily deployed in the area, used tear gas, water cannon, sound bombs and buckshot to disperse the demonstrators.
Bahrain's Information Authority said Mohammed Ali Ahmed Mushaima, 23, had been in hospital since August and died of complications from sickle cell disease.
Opposition activists said the authorities caused his death by denying him proper treatment. His funeral was held on Tuesday.
Mushaima was jailed for seven years in March 2011 for "vandalism, rioting, assaulting a police officer and resisting arrest".
The protesters, mainly from the Shia majority, have been demanding a bigger role for elected representatives and less power for the ruling al-Khalifa family, who are Sunni Muslims.
Despite a crackdown on the protests last year, that included two months of martial law, clashes between police and protesters occur almost daily in Bahrain, where the US Fifth Fleet is based.