Shi'ite Muslims clashed with riot police in villages across Bahrain on Thursday, the anniversary of a government crackdown last year on a pro-democracy uprising in the Gulf Arab state.
Witnesses said youths and police faced off in Shi'ite areas including Sitra, Diraz, Malkiya, Saar, Jidhafs, Tubli and Bilad al-Qadeem, all districts outside or on the edge of the capital Manama.
Police, who are overwhelmingly Sunni Muslim, fired tear gas, rubber bullets and sound grenades while youths threw petrol bombs - a pattern that has repeated itself almost daily for months.
But the clashes were more intense because of the anniversary of the breakup of protests across the country by force. There were unconfirmed reports of several injuries among protesters from direct hits by tear gas canisters.
Majority Shi'ites, who complain of political and economic marginalisation, led a protest movement that erupted in February last year after revolts in Egypt and Tunisia, only to be crushed in mid-March when the government imposed martial law and brought in Saudi and United Arab Emirates troops.
Foreign troops entered Bahrain, an island state whose tourism and banking sectors are struggling to recover from the unrest, on March 14 and emergency law was declared on March 15.
Security forces have not used live fire since then.
The opposition call the Saudi and UAE intervention an occupation; the government says it was to prevent any effort by Iran to help its fellow Shi'ites.
The Sunni ruling Al Khalifa family dominates government and has resisted demands to give the parliament full powers to legislate and form governments.
It describes youths clashing with police as hooligans and says Shi'ite leaders should do more to stop them.