Tens of thousands of Shiite Muslims (search) marched in Baghdad on Monday to demand early elections, the biggest public display of Shiite political power here since the collapse of Saddam Hussein's Sunni-dominated regime.

The protest aimed to send a message to the United Nations and the White House that Shiites will not accept a U.S. formula for transferring power by July 1 to a legislature selected in regional caucuses instead of by a direct vote as the Shiite clergy demands.

Hours after the march, U.S. and Iraqi officials asked the United Nations to send a team to study the possibility of holding elections in Iraq. Secretary-General Kofi Annan (search) indicated that he was leaning toward granting the request but wanted more details. He said he hoped to make a speedy decision.

"On the elections, I have indicated that I ... don't believe there may be enough time between now and May to hold elections," Annan told reporters. "But the team will go down and look into that further and report to me."

The protesters, estimated by reporters at up to 100,000, carried posters of Grand Ayatollah Ali al-Husseini al-Sistani (search), Iraq's most influential Shiite cleric, whose opposition to the U.S. plan threatens to delay the July 1 deadline for the end of the U.S.-led occupation.

Al-Sistani also wants an elected assembly to ratify security accords governing the presence of coalition troops after July 1 as well an interim constitution to take effect until a final charter can be drafted and ratified in 2005.

Shiites are believed to comprise about 60 percent of Iraq's 25 million people. U.S. authorities cannot afford to alienate a community which has so far generally avoided attacks on coalition forces.

"The sons of the Iraqi people demand a political system based on direct elections and a constitution that realizes justice and equality for everyone," Hashem al-Awad, a representative of al-Sistani, told the crowd. "Anything other than that will prompt people to have their own say."

In response, the crowd chanted: "Yes, yes to elections! No, no to occupation!"

Saying he had a message for the United Nations and the U.S.-led coalition, al-Awad told the crowd: "No regime can exist without a role for the people."

Of the protests, Bremer said in New York: "There are demonstrations all the time, some of them not always very friendly to the coalition, I might add, but they're peaceful and we welcome it."

U.S. officials insist early elections are not feasible because of Iraq's precarious security situation, the absence of an election law and the lack of voter rolls. An election could also hand power to well-organized groups such as remnants of Saddam's now-banned Baath party and religious extremists rather than Iraqis willing to cooperate with the coalition.

The security risks were underscored by a devastating bomb attack Sunday at a gate to the coalition's headquarters compound. The Iraqi Health Ministry on Monday raised the death toll from the attack to 31, with 121 people wounded. Most of the victims were Iraqis.

Under an agreement promulgated on Nov. 15, Iraqis won't have a direct vote until next year when they choose delegates to draft a permanent constitution. They will vote twice again in 2005, once to ratify a new constitution and again to elect a new assembly.

U.S. officials here have said they hope the U.N. team will determine that al-Sistani's election demand is not feasible. Asked about the possibility of reconsidering his opposition to an early ballot, Bremer told reporters in New York that the question was legitimate "and one where the U.N., with its expertise in elections, can offer a perspective."

Many participants in Monday's protest said Iraq would have been ready for a general election by June 30 if the coalition had begun preparations soon after the fall of Saddam's regime in April. Others believed the caucus system is just another way to appoint members of the transitional legislature.

"We are demanding democracy. And that's what America came to give us," cleric Faras al-Tatrasani, said. Another protester, Hassan al-Nouri, said the Americans "want to fill the assembly with people who support them. We shall march and march until they agree to an election."

Scores of Iraqi policemen and hundreds of organizers ensured the march went peacefully. Volunteers walked ahead of the protesters, carefully examining the three-mile route for possible roadside bombs.

Two U.S. helicopters hovered overhead as the crowd converged on Al-Mustansariyah University. The march came to a halt when the call for the midday prayer rang out from a Sunni mosque along the route. Turning to face the Muslim holy city of Mecca, they stood still while loudspeakers played the Shiite prayer call.

The outpouring of support for al-Sistani's position reflects the problems that Washington could face if it decides to ignore the wishes of the elderly cleric and his supporters.

"All the people are with you, al-Sistani," the crowd repeatedly chanted. Many banners carried by protesters pledged their readiness to die for al-Sistani.

In other developments Monday:

-- An advance team of more than 30 Japanese soldiers reached southern Iraq -- the first time that country's troops have been in a conflict zone since World War II. The Japanese contingent will grow to 1,000 by March to purify water supplies, rebuild schools and provide medical care. They will carry arms for self-protection but their role will be noncombatant.

-- Three Arab foreigners died and U.S. troops seized weapons after a gunbattle early Monday at what Iraqi police described as a "terrorist safehouse" in a Baghdad suburb.