Bahraini protesters marking the third anniversary of an Arab Spring-inspired uprising clashed with security forces on Friday in the capital Manama and outlying villages, witnesses said.
Hundreds of men and women took to the streets in parts of the capital and in Shiite villages that have been at the forefront of the campaign among the Gulf state's Shiite majority for a consitutional monarchy in the Sunni-ruled Gulf kingdom.
They were met with tear gas and birdshot, the witnesses said, adding that several demonstrators were wounded.
The clashes came ahead of an afternoon march called by an influential cyber-group on the capital's Pearl Square, where demonstrators camped out for a month in early 2011 before being violently dispersed by troops.
Bahrain announced in June that it had arrested leading members of the February 14 youth coalition, accusing it of links to Shiite Iran.
Saudi-led Gulf troops deployed in Bahrain on the eve of the March 2011 crackdown, manning key positions while the tiny kingdom's own security forces dispersed the protesters.
The Pearl Square roundabout and its central monument, which were a symbol of the uprising, were later razed and the site remains heavily restricted.
"Down with Hamad," protesters, some wrapped in white shrouds and others covering their faces, chanted on Friday referring to the king.
"We will never surrender," they shouted as police helicopters hovered overhead and police forces, deployed heavily across the kingdom, set up checkpoints outside Shiite villages, witnesses said.
Earlier this month, Bahrain toughened jail sentences for offending King Hamad, announcing that such an offence will carry a minimum one-year and a maximum seven-year term, as well as a fine of up to $26,000 (19,260 euros).
The Shiite opposition called for three days of protests to mark the anniversary as it seeks to give new momentum to its campaign for the ruling Khalifa family to surrender its grip on all key cabinet posts in favour of an elected government.
- Mass rally planned -
The main Shiite opposition party Al-Wefaq, which has boycotted parliament since the uprising, said several areas had observed a complete shutdown Thursday following its call for a strike on the last day of the working week in Bahrain -- ahead of a mass rally the bloc is planning for Saturday.
The interior ministry insisted that "business largely progressed as normal throughout the day" on Thursday.
"In general, citizens went about their daily business and work was normal in government and private organisations," said a ministry statement.
But it did confirm "some cases of rioting and vandalism in villages where groups blocked roads with bricks, iron spikes, debris and oil".
It said 29 people were arrested.
Amnesty International on Thursday condemned Bahrain's "relentless repression" of dissent and said it feared a violent crackdown on the anniversary demonstrations.
The International Federation for Human Rights (FIDH) on Thursday urged Bahrain "to take immediate measures to restore the rule of law, to put an end to ongoing human rights violations and to comply with their reiterated pledges before the population of Bahrain and the international community".
The FIDH says at least 89 people have been killed since the uprising began three years ago.
In a speech published on the referendum anniversary by the official BNA news agency, King Hamad affirmed the kingdom's "commitment to complete reform in accordance with our circumstances, national interests, identity and values".
Two rounds of national reconciliation talks between the opposition and the government failed to make any headway on a settlement in the strategic archipelago just across the Gulf from Iran.
Bahrain is the home base of the US Fifth Fleet.