MANAMA, Bahrain: As a Brussels-based think tank warned Bahrain could slide into violence owing to discrimination against its own citizens, thousands of Bahrainis on Friday took to the streets backing opposition demands for wider powers for the elected parliament.

The demonstrators rallied in Sanabis village west of Manama, chanted slogans and demanded constitutional reforms.

"We demand constitutional reforms now. We demand a freely elected parliament." screamed the crowd.

"Taking to the streets does not contradict dialogue with authorities... it complements it," Sheikh Ali Salman, head of the Islamic National Accord Association (INAA), the main political formation of Bahrain's Shias who make up majority of the kingdom's 400,000 citizens. More than 80 percent Bahrainis are Shias.

Shias complain they are discriminated against by the country's leadership.

"The opposition is counting on the king to introduce constitutional amendments because he played a major role in the reform drive," Ali Salman said.

Salman and leaders of three allied groups -- the leftist National Democratic Action Association, the pan-Arabist Nationalist Democratic Rally, and the Shia Islamic Action Association -- led the protest, the second since late March.

"People are demanding immediate constitutional reforms which will guarantee more rights to the people," said Abduljalil Singace, an INAA spokesman at the rally. "This campaign for reforms will continue until the demands of the people are met."

Policemen moved through the demonstration in vehicles but did not interfere; a police helicopter hovered over the area. Traffic police struggled to keep the traffic moving and the rally ended peacefully.

Meanwhile, the International Crisis Group warned in a report that Bahrain could face violence unless steps are urgently taken to address political and social grievances, particularly those of the Shia majority.

While the government has taken a number of steps since Hamad announced his reform plan four years ago, "reform has been uneven and appears as simply the royal family institutionalizing its grip on power," the think tank said.

Moreover, the government "has done virtually nothing to tackle sectarian discrimination and tensions," it said calling on the US to "praise Bahrain's reformist rhetoric a little less and urge the government to match it with action a little more."