To prepare for a potential humanitarian crisis in Iraq, the Bush administration is planning to ask the Security Council to transfer future control over Iraq's purchase of food and supplies from Baghdad to the United Nations, whether or not the council supports a U.S.-led invasion of Iraq.

The administration, anticipating a day when Iraqi President Saddam Hussein no longer rules, wants the United Nations to have the authority to acquire goods quickly during a war. Some U.S. officials are worried that a rejection of force could hinder relief work, if the Security Council proves reluctant to change the arrangement that permits Iraq to spend its oil receipts.

Unresolved is the long-term role the United Nations might play in the administration of Iraq and its reconstruction. Although U.S. officials traveled to New York this week to brief executives of the world body, they were unable to answer questions about who would run Iraq after an initial post-conflict phase.

"They want to be formally told from the highest levels of the U.S. government what we want their role to be. The answer to that is we don't know," a U.S. official said. "All we can say is that on relief, we're doing everything we're able to arrange a major U.N. role."

A frustrated senior U.N. official said that means "we plan, but we wait."

Beyond the narrow resolution transferring spending authority during wartime, U.S. planners are in the early stages of discussion about a more ambitious postwar Security Council resolution that would set out details of how Iraq would be governed. The measure, if pursued, would cover such sensitive issues as management of the Iraqi oil industry, officials said.

Such Security Council involvement is essential, said Mark Malloch Brown, director of the U.N. Development Program. He noted that the war in Kosovo was fought without U.N. authorization, but was followed by a resolution establishing legal authority for building peace.

"There's going to have to be a resolution," Malloch Brown said. "Under the Geneva Convention, an occupying force has the right to continue day-to-day administration and management of a country, but doesn't have the right to start reorganizing the country's political institutions and legal system."

The Bush administration has said it intends to run Iraq with the help of foreign partners, international agencies and Iraqi ministries after Hussein falls. Policymakers in the administration remain divided about who should be in charge, not least because the post-Hussein circumstances remain unknown.

The designs of relief operations are more advanced than plans for rebuilding Iraq, according to U.S. officials. Administration military and civilian agencies are working to arrange deliveries of food, water and medical supplies on the assumption that existing networks would be interrupted by armed conflict. The U.S. government has been negotiating a management role for the U.N. World Food Program.

To avoid creating a bottleneck, U.S. and British officials want to transfer spending authority over Iraqi oil revenue to the United Nations, allowing access to $2.5 billion in food and supplies already bound for Iraq, as well as Iraqi oil revenue collected under existing U.N. sanctions.

The new resolution to ease emergency relief is being designed by U.S. and British diplomats to include "absolutely nothing controversial," a U.S. official said. It would cover financial arrangements, increase the number of border crossings that can be used for shipment and modify U.N. monitoring, among other provisions.

One senior U.S. relief worker predicted that the divided Security Council would pull together to prevent a humanitarian calamity if the White House chooses war. He said political concerns would be overcome by a desire to limit harm to Iraqis. A number of foreign diplomats agreed, adding that future resolutions could help heal the council after the bitter fight over force.

"I don't think that the U.N. is going to let people starve," the U.S. relief official said.

Staff writer Karen DeYoung contributed to this report.