Pro-reform legislators fired a new volley in their latest political crisis with Iran's hard-liners Sunday, passing a law aimed at restricting the power of a council that conservatives used to bar liberal candidates from running in elections.

The law poses a challenge to the Guardian Council (search), the unelected body controlled by hard-liners that has broad powers to overrule decisions of the elected government. The council could nullify the new law, but that would likely stoke the crisis.

The reformist-dominated parliament approved the bill, categorized as "triple-urgent" — the highest designation of importance for legislation, used when the parliament feels that the country is in great political or military danger.

It was the first time since Iran's 1979 Islamic revolution that the parliament has approved a triple-urgency bill.

"We demanded the triple-urgency bill and approved the amendments because we feel the very basis of people's choice and democratic principles are trampled," reformist lawmaker Reza Yousefia (search)n told The Associated Press.

Reformists have been protesting since the Guardian Council this month disqualified more than 3,000 would-be candidates from running in February's legislative elections, including 80 liberal members of parliament. The decision was seen as an attempt to assure a new hard-liner majority in parliament.

The bill passed Sunday, during a parliament session aired live on Tehran (search) radio, amends the Elections Law, requiring the Guardian Council to allow all lawmakers or candidates approved in past elections to run for office unless strong legal documentation proves them unfit.

It also requires the council to approve anyone seeking office who have been deemed loyal to Islam and the ruling Islamic establishment by local trustees. That clause was aimed at eliminating politically motivated disqualifications.

"It's a historic test for the Guardian Council, which claims to be following the leader. The bill is actually what the leader said in a way a few days ago," Yousefian said.

Last week, Iran's supreme leader, Ayatollah Ali Khamenei, asked the council to reconsider the disqualifications, but the Council has moved slowly and defended the disqualifications. Khamenei appoints the members of the Guardian Council, and some reformist legislators have said it would not have acted without his approval.

While the parliament approved the general outlines of the bill, details were to be debated later Sunday in the presence of 11 Guardian Council members. The 12th seat on the council is empty after the expiration of one member's term.

The battle over who can run in Feb. 20 elections has turned into Iran's worst political crisis in years, with powerful hard-liners in Iran's Islamic government seeking control of the 290-seat Majlis now dominated by the president's liberal allies.

Hard-liners claim those disqualified — more than a third of 8,200 hopeful candidates — had failed to meet legal criteria for being members of parliament.