Police in Bahrain have fired teargas and stun grenades in clashes with hundreds of stone-throwing anti-government protesters marching in the old market area of central Manama.
The protesters tried to gather on Friday in several parts of the capital after a call sent out by February 14 youth activists, witnesses said.
The interior ministry said on its Twitter account that "saboteurs" threw Molotov cocktails at the police who then intervened to restore order.
Several people were detained as security forces moved against protesters, led by the daughter of jailed opposition leader Abdulhadi al-Khawaja.
A separate demonstration called by Al-Wefaq, the main opposition group, took place without any incident at a thoroughfare west of Manama. This one was permitted by the authorities, unlike the march in central Manama.
Thousands rallied in that peaceful demonstration carrying Bahraini flags and banners that read "Stop shedding our blood," witnesses said.
Demonstrations are common on Fridays in Bahrain since it was shaken by a protest movement last year, demanding a constitutional monarchy in the Gulf kingdom.
The International Federation of Human Rights says 80 people have died since the start of the revolt. The interior ministry says 700 people have been wounded, including police..
Bahraini authorities accuse regional Shia power Iran of encouraging the unrest and have vowed a tough response to violent protests as talks with the opposition have stalled.