Bahraini police forces used tear gas to disperse protesters on Tuesday and made at least 20 arrests, as scores of people took to the streets of Manama to mark the first anniversary of anti-government demonstrations, dpa reported.
Protesters tried to reach Pearl Square, the epicentre of last year's Shiite-led protests against the kingdom's Sunni Muslim rulers, which has been closed by security forces since March.
Several people were injured in clashes between security forces and protesters, who threw rocks and petrol bombs, witnesses said.
The Interior Ministry said it had arrested "a group of saboteurs who tried to disrupt traffic," according to the state news agency BNA.
The Cairo-based Arabic Network for Human Rights Information group condemned what it called the "shameful Arab and international silence" over events in Bahrain, where people "are still facing excessive violence by security services."
"On the first anniversary of the revolution, ANHRI calls on the international community and the Arab League to take swift actions pressuring the Bahraini authorities to cease the violence used against peaceful protests," the group said.
It also called for the release of opposition leaders, rights activists, and prominent bloggers currently detained in Bahraini prisons.
Clashes also took place on Monday, when security fired tear gas to disperse thousands of protesters.
The death toll from nearly a year of protests stands at 60, according to opposition groups.