Opposition demonstrators have clashed with police in Bahrain as they marked the third anniversary of Arab Spring-inspired anti-government protests.
It was the first of three days of protests called by the Shia-led opposition to mark Friday's anniversary as they seek to give new momentum to their campaign for a constitutional monarchy in the Sunni-minority-ruled Gulf state.
Clouds of tear gas billowed from the streets of several Shia villages outside the capital Manama as security forces attempted to dismantle roadblocks of burning tyres, witnesses told the AFP news agency.
The opposition has been demanding that the ruling Khalifa family surrender its grip on all key cabinet posts in favour of an elected government.
"Down with Hamad," the protesters chanted, referring to the king, AFP reported. "Only to Allah we kneel."
The protesters defied a heavy security presence to set up makeshift roadblocks of felled trees and burning tyres in several villages, where persistent demonstrations have sparked repeated clashes with police.
The Interior Ministry said police "confronted groups of vandals and cleared blocked roads".
The main Shia opposition party Al-Wefaq, which has boycotted parliament since the uprising, posted images of protesters being tear gassed and police in riot gear patrolling deserted streets.
Al Jazeera could not independently verify those images.
The underground February 14 youth coalition has called on its supporters to on Friday try to reach Pearl Square, where demonstrators camped out for a month before being violently dispersed by Saudi-backed troops in March 2011.
The Pearl Square roundabout and its central monument, which were a symbol of the uprising, were later razed and the site remains heavily restricted.
At least 89 people have been killed in the three years since the launch of the uprising, according to the International Federation for Human Rights.
Two rounds of national reconciliation talks have failed to make any headway on a settlement in the Gulf archipelago, which is home base to the United States Fifth Fleet.