Iraq's most powerful Shiite cleric, Ayatollah Ali al-Sistani, has demanded direct elections, challenging a US plan for transferring power to Iraqis by June 30.

Sistani's allies have indicated the cleric would abide by a UN decision, a key reason why the Bush administration, which had previously scorned the world body, now wants Annan to give the process legitimacy.

UN officials have been as dubious as the United States about direct elections, not just because of the short time left to organize them, but because of the violent atmosphere, which they say tends to favor extremists.

The United Nations withdrew its international staff from Iraq in October after an attack on its headquarters in Baghdad killed 22 people in August.

"Once I'm satisfied that the CPA (US-led authority in Iraq) will provide adequate security arrangements, I will send a mission to Iraq in response to the requests that I received," Annan said in a statement released during a visit to Paris.

"The mission will ascertain the views of a broad spectrum of Iraqi society in the search for alternatives that might be developed to move forward to the formation of a provisional government."

Elections would favour Shiites, who make up an estimated 60 percent of Iraq's 25 million people.

The US plan envisages a complicated system of caucuses in 18 Iraqi provinces.

A phased transition to self-rule would allow for time to build institutions, form political parties and create alliances that cut across religious groupings.

AFP adds: The US-led coalition welcomed yesterday a UN decision to send a team of experts to Iraq to study whether elections can be held before a planned transfer of power and agreed to provide adequate security measures.

The coalition "welcomes the UN Secretary General's statement of intent to send a mission to Iraq to evaluate the feasibility of elections before June 30," spokesman Charles Heatly told AFP.

Earlier Tuesday, Kofi Annan agreed to a US and Iraqi request to send a team of experts to Iraq amid demands from the country's majority Shiite Muslim population for elections before the planned introduction of self-rule in June.

"As soon as I have been persuaded that the coalition's provisional authority will take adequate measures to assure security, I will send a mission to Iraq as I have been requested," Annan said in a statement released in Paris.