Iraq's new interim government won crucial recognition Thursday from Iraq's most revered cleric, Grand Ayatollah Ali Sistani, the Iraqi Shiites' supreme religious leader.

Sistani, in a written statement issued by his office in the holy city of Najaf, shied away from a formal endorsement of the new government. But he said it could make itself worthy by improving life for Iraqis and by erasing "the consequences" of the U.S. occupation.

He said the interim government would be denied "popular acceptance" unless it "proves through practical and clear steps that it seeks diligently and seriously to achieve these tasks."

Sistani, joining an international debate, also called for the U.N. Security Council to move quickly give "political, economic and military" sovereignty to Iraqis.

Sistani's rare comments were considered highly significant. He holds great sway among Iraq's majority Shiite population, so much so that he was able to force the United States to significantly modify its timetable for Iraqi self-government earlier this year.

While his words were not enthusiastic, they were far more welcoming than anything he had said about the now-dissolved Iraqi Governing Council and contrast dramatically with continued insurgent operations by rival Shiite cleric, Moqtada Sadr and his anti-occupation militia. They also reflected his continued unease with the U.S. occupation of the country.

"Not all segments of Iraqi society and its political forces are represented in an appropriate manner" in the new government, Sistani said. But "the hope is that this government will prove its worthiness and integrity and its firm readiness to perform the mammoth tasks it is burdened with."

Among those tasks, he said, are the restoration of security, the provision of basic services and free and fair elections in the year ahead.

The interim government, led by Prime Minister Ayad Allawi, was announced Tuesday On June 30, it assumes what President Bush has called "full sovereignty," though the definition of "full" remains the central focus of debate in the U.N. Security Council, which is considering a resolution proposed by the U.S. and Britain giving an international imprimatur to the new regime.

Sistani's statement on that resolution came as the pressure intensified for the U.S. and Britain to spell out more explicitly how much authority the Iraqi government will have.

France, Russia, China -- three of the five nations with Security Council vetoes -- and Germany, Chile and Algeria are all urging changes or considering amendments to a new draft resolution that the United States and Britain circulated Tuesday, envoys said.

Several Security Council countries want more specifics in the resolution on the U.S.-led multinational force to ensure Iraq has the right to determine the length of its deployment and its mandate. They also want to spell out what the "return of full sovereignty" means to ensure that the U.S.-led occupation ends, U.N. sources say.

Bush, at a photo opportunity Thursday with Australian Prime Minister John Howard, reiterated previous assurances that "the government of Iraq will be fully sovereign." That means, he said, "that our coalition will be there with the consent of the fully sovereign government. And that's what the U.N. resolution is going to say.

"Now, Prime Minister Allawi has made it clear that he wants help from the coalition to deal with the security issues so that the country can have free elections," said the president. "That's what he has said. He is the prime minister and that's what he has said."

Bush said, "We've had these arrangements before -- these security arrangements with other countries. We're good about forging relationships on the ground, respecting the sovereignty of the country and at the same time being able to do our jobs that the host government expects to be done."

Secretary of State Colin L. Powell, in an interview with Middle East Broadcasting, said that the Iraqi government would have no "veto" over U.S. military actions -- effectively contradicting British Prime Minister Tony Blair.

According to wire service reports of the interview, Powell said the fully sovereign government could make agreements with the U.S. military, but added: "There could be a situation where we have to act and there may be a disagreement and we have to act to protect ourselves or to accomplish a mission.

"The resolution does not talk about a veto over any military operations," Powell said. "You can't use the word 'veto'."

Barbash reported from Washington.