|Tens of thousands of Bahrainis demonstrated in Budaiya to demand democratic reforms [Reuters]
The protesters began marching along a main road near the city on Friday in response to a call from leading Shia cleric Sheikh Isa Qassim who urged people to renew their calls for greater democracy.
Tens of thousands of Bahrainis have demonstrated outside the capital Manama to demand political reforms, a year after the Gulf Arab state crushed an uprising, witnesses said.
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," Qassim said before the march, during his weekly sermon in the Shia village of Diraz.
He had promised to personally lead the march, his most high-profile action in more than a year of unrest.
A photographer with the Reuters news agency said the main Budaiya road in the area of Diraz, and Saar, west of Manama was packed, just one hour before the protest was set to begin.
"It is the biggest demonstration in the past year. I would say it could be over 100,000," he said.
Nabeel Rajab, president of the Bahrain Centre for Human Rights, told Al Jazeera by phone from Manama that "thousands of security forces" had been deployed to close down roads leading to the protest site.
"The message is that people are not happy with the government. We have clear demands: an elected government, a parliament with power, an end to sectarian discrimination, a clear redistribution of wealth and power and all demands guaranteed by the international convention on human rights," he said.
Rajab added that Friday's protests were "the biggest in our history".
The country's majority Shia population were in the forefront of last year's protest movement in Bahrain, which erupted in February after uprisings in Egypt and Tunisia.
The Sunni Muslim ruling Al Khalifa family crushed the protests one month later, imposing a period of martial law and bringing in Saudi and United Arab Emirates troops to restore order.
An independent commission of inquiry, formed and funded by Bahrain's government, investigated the protests in February and March 2011.
The commission found that "Thirty-five deaths occurred between February 14 and April 15, 2011 that have been linked to the events of February and March 2011. The deaths of 19 of these civilians have been attributed to security forces."
Among other findings, the commission reported that "Many detainees were subjected to torture and other forms of physical and psychological abuse while in custody".
Bahrain, where the US Fifth Fleet is based, has remained mired in crisis and Shia youths clash daily with riot police.
The unrest has slowed the economy in what was a major tourism and banking hub in the Gulf region.
Tension has risen in recent weeks around the February 14 anniversary of the uprising, with security forces maintaining a tight grip on the traffic intersection that protesters originally occupied.
Pro-government Sunni groups have organised counter rallies, warning the 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 say the opposition is loyal to Shia Iran, a charge the opposition parties deny. Analysts say Riyadh does not want Bahrain to agree to reforms that empower Shias.
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.