Nabil Al-Jurani / AP
Followers of Shiite cleric Muqtada al-Sadr, seen in the posters, chant anti-Saudi and Bahraini governments slogans while waving Bahrain flags during a demonstration in Basra, Iraq's second-largest city, on March 9, 2012.
Tens of thousands of Bahrainis demonstrated on Friday to demand democratic reforms, stepping up pressure on the U.S.-allied government with the biggest protest yet in a year of unrest.
They began marching along a highway near Manama in response to a call from leading Shiite cleric Sheikh Isa Qassim, who urged people to renew their calls for greater democracy.
A live blog showed images of the protesters carrying banners denouncing "dictatorship" and demanding the release of detainees.
"We are here for the sake of our just demands that we cannot make concessions over and we stick with them because we have sacrificed for them," Sheikh Isa Qassim said before the march in his weekly sermon in the Shiite village of Diraz.
Qassim and other Shiite clerics led the march.
"It is the biggest demonstration in the past year. I would say it could be over 100,000," said a Reuters photographer after protesters filled up the main Budaiya highway in the area of Diraz and Saar, west of Manama.
Security forces fired tear gas at a small group of protesters, but the rally was mostly peaceful, the BBC reported.
Activists had called for the biggest rally since the Bahraini authorities quelled a popular protest with help from Saudi troops more than a year ago.
Later, hundreds of protesters broke away from the march to walk down the main highway into Manama in an attempt to return to a traffic intersection that protesters occupied for a month during last year's uprising.
Activists said riot police blocking the road fired tear gas and the interior ministry said protesters threw stones.
The government, pressed by its Western allies to allow peaceful expression of dissent, has allowed more opposition protests in recent months.
The BBC reported some protesters chanted "Down, down Hamad," referring to King Hamad bin Isa Al Khalifa.
A statement from the royal court praised a small Friday rally of several hundred government loyalists under the name "Fateh Gathering", and the Qassim march, as signs of democratic maturity.
"The events at the Fateh Gathering as well as the gathering in the Northern Governorate are a source of pride for Bahrainis as a model of correct democratic behavior," state news agency BNA reported.
Majority Shiites were in the forefront of the protest movement which erupted in February 2011 after uprisings in Egypt and Tunisia. The Shiia population makes up about 70 percent of the country's 525,000 citizens.
The ruling Sunni Muslim Al Khalifa family crushed the protests a month later, imposing martial law and bringing in Saudi and United Arab Emirates troops to help restore order. It accused the Shiite power Iran of fomenting the unrest.
On Friday, Iraqi followers of Shiite cleric Moqtada al-Sadr demonstrated in Basra in support of the Bahraini opposition. Around 3,000 people chanted anti-Saudi slogans and carried Bahraini and Iraqi flags.
Bahrain, where the U.S. Navy Fifth Fleet is based, has remained mired in crisis and Shiite youths clash daily with riot police. The unrest has slowed the economy in what used to be a major tourism and banking hub.
Tension has risen around the February 14 anniversary of the uprising, with security forces maintaining a tight grip on the intersection formerly known as the Pearl Roundabout, which remains closed.
Pro-government Sunni groups have organized smaller counter-rallies, warning authorities not to enter into a dialogue on reforms that could give the elected parliament legislative clout and the power to form governments.
Those groups look to Sunni power Saudi Arabia as a key ally and demonize the opposition as loyal to Iran, a charge the opposition parties deny. Analysts say Riyadh does not want Bahrain to agree to reforms that empower Shiites.
Activists say at least 27 people have been killed in the unrest since June, many from the effects of tear gas. The government disputes the causes of death.
King Hamad appeared to dismiss the opposition last month, saying they were disunited.
Qassim said Friday's march would show how strong the opposition was. "The march will either prove you are only an isolated minority making demands, or that the demands are widely popular," he said in his sermon, which was posted on YouTube.
Next month, the Bahraini Grand Prix motor race is due to be held in the country, according to the BBC.
Reuters contributed to this report.
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