The Bahraini clashes are being largely suppressed Bahraini police dispersed protesters who made several attempts Tuesday to mark the anniversary of last year's uprising by marching to the site of the protest that was brutally crushed, witnesses said.
Several protests took off from Shiite villages on the outskirts of Manama, with youth trying to reach the capital's former Pearl Square, where democracy demonstrators camped for a month last year before being forcefully driven out.
Protesters marched from Sanabis, Deih and Jidhafs, which lie few kilometres (miles) west of Manama, despite police warning that protests would be dispersed, witnesses said.
"Down with (King) Hamad!" they chanted, referring to the Sunni monarch whose Al-Khalifa has ruled the Shiite-majority Gulf kingdom since the 18th century.
The Coalition of the Youth of February 14th Revolution, a hardline group that operates apart from the political opposition led by Al-Wefaq, declared Tuesday the day to return to the square that was razed after the mid-March crackdown.
All of us are returning" to the square, read a call for protest posted on its Facebook page, designating 6:40 am (0340 GMT) as the starting time.
The coalition posted footage of youth dressed in white Islamic death shrouds running through some alleys claiming they were heading to the square that is heavily protected by security forces.
It also posted a picture of women dressed in traditional black abayas (cloaks) standing close to the square flashing the victory sign.
 On Tuesday, Al-Wefaq accused security forces of waging a campaign of arrests against people who took part in protests. It said 13 people were detained, including female activist Maasouma al-Sayyed, who is reported to have reached the square area.
It said police raided Shiite villages where many houses were hit by tear gas canisters, and that several arrests took place overnight.
Activists have called for demonstrations on Monday and Tuesday at the square.
But the Al-Wefaq-led alliance of opposition groups said Monday following a large protest organised outside Manama that although Pearl Square has "become a symbol" for protest, it is not the only one, clearly distancing itself from the call to return.
"All squares and streets of the country are sites that we use to renew our vows to press ahead in our struggle to achieve our demands," including a powerful parliament, representative government and redrawn "fair" electoral constituencies, it said.
Bahraini security forces, boosted by Gulf troops that rolled in from neighbouring Saudi Arabia, quelled the month-long protest that appeared to take a cue from Arab Spring uprisings.
Human rights activist Nabeel Rajab, who has been holding daily protests in Manama with a group of activists, called for another march to Pearl Square.
"Let's drive at 3:30 pm (1230 GMT) towards the square, step out of cars and run to the (Pearl) roundabout," he wrote on his twitter accout.
Security forces in Bahrain already fired tear gas and stun grenades at protesters trying to occupy a landmark square in the nation's capital Manama on Monday.
Monday's march by thousands of opposition supporters to Manama's Pearl Square was the largest attempt in months to retake the central roundabout that served as the epicentre of weeks of protests last year by Bahrain's Shiite majority against the ruling Sunni dynasty. The government deployed thousands of security forces to prevent the opposition from staging a mass rally to mark Tuesday's one-year of the revolt.
Bahrain imposed martial law in March to quell the protests. Emergency rule was lifted in June, but clashes still occur on an almost daily basis. An independent commission later found the security forces guilty of abusing protesters and detainees.
Some protesters hurled firebombs and rocks after the security forces fired tear gas. In an area about six miles (10 kilometres) west of central Manama, some demonstrators stood atop Bahrain's ancient burial mounds — some more than 5,000 years old — waving flags featuring the image of Pearl Square's six-pronged monument.
More than 50 police vehicles filled a site that protesters have dubbed "Freedom Square," which hosted several government-sanctioned opposition gatherings last week.
After the government imposed martial law last March in response to the demonstrations, security forces stormed the protesters' encampment at the landmark square in a bid to crush the uprising. The authorities then razed the towering white monument that stood in the centre of the plaza.
The now heavily guarded square holds great symbolic value for Bahrain's opposition movement, and protesters have repeatedly tried to reoccupy it. But authorities have effectively locked off the capital to demonstrations since March.
Emergency rule was lifted in June, but street battles between security forces and protesters still flare up almost every day in the predominantly Shiite villages around the capital.
At least 40 people have been killed during months of unprecedented political unrest in Bahrain, the Gulf country hardest hit by upheaval during last year's Arab Spring protests. Neighbouring Saudi Arabia and other Sunni-ruled Gulf states dispatched troops to Bahrain in March to help crush the protests.
Shiites account for about 70 percent of Bahrain's population of some 525,000 people, but say they have faced decades of discrimination and are blocked from top political and security posts.
Bahrain's Sunni rulers have promised reforms, although they refused to make the far-reaching changes the protesters and the main Shiite group, Al Wefaq, have demanded. These include ending the monarchy's ability to select the government and set key state policies.
US State Department spokeswoman Victoria Nuland expressed concern over the violence Monday and said Washington wants to see demonstrators stage peaceful protests and for security forces to "exercise restraint and operate within the rule of law and international judicial standards."
In London, Amnesty International said on Monday that the Bahraini government remains far from delivering the human rights changes that were recommended by an independent international commission. The group urged more measures to show that the steps were "more than a public relations exercise."
Amnesty called for releasing prisoners held on protest-related offenses and moving ahead with investigations into alleged abuses by security forces and others.