American taxpayers should demand accountability from an institution that depends on their funding. Luckily, that's finally starting to happen. As the United Nations Oil for Food scandal continues to unfold, Congress is beginning to flex its investigative muscle. Five different committees are investigating the largest financial fraud of modern times.

With the arrival of new chairmen for both the House and Senate Appropriations committees in January, it's time for Congress to withhold the generous contribution that U.S. taxpayers bestow on the United Nations each year -- until and unless it fully cooperates with these and other concurrent investigations.

There is mounting outrage on Capitol Hill over the management of Oil for Food. The U.N. program was supposed to protect the Iraqi people from international sanctions targeted at the Iraqi dictatorship. Instead, it served as a giant slush fund, enriching Saddam Hussein even as people starved to death.

Recent Senate hearings on the scandal doubled the previous estimate, to $21.3 billion, of Saddam's plunder. An investigation by the House International Relations Committee concluded that Saddam used some of that money to fund Palestinian terrorism.

New revelations also have emerged regarding Kojo Annan, the son of U.N. Secretary-General Kofi Annan. Kojo now admits that, until this year, he was on the payroll of a Swiss contractor hired to inspect humanitarian goods brought into Iraq through the Oil for Food program. Annan had claimed such payments ended in 1999.

A lack of U.N. cooperation has compounded congressional anger. Minnesota Sen. Norm Coleman, chairman of the Investigations Subcommittee, and his Democratic counterpart, Michigan's Carl Levin, have accused Kofi Annan of blocking efforts by Congress to obtain U.N. documents relating to Oil for Food, including 55 internal audit reports. Annan also refuses to allow congressional investigators to interview U.N. officials.

The breathtaking arrogance displayed by Annan and the U.N. leadership is simply unacceptable. Oil for Food has further eroded the American public's trust in the U.N. and exposed potentially irreconcilable fault lines between the U.S. government and the U.N. To coerce a recalcitrant U.N. to cooperate, Congress should apply powerful financial pressure on the U.N.

That pressure has rightfully increased in recent weeks. Rep. Roger Wicker of Mississippi and 19 of his House colleagues joined Sen. Coleman in calling on Kofi Annan to resign. Arizona Rep. Jeff Flake and 77 of his House colleagues have signed on to legislation to reduce the annual U.S. contribution to the U.N. by 10 percent in 2005 and 20 percent in 2006, or until the U.N. adopts financial reforms specified in the Flake bill. Finally, senior House Appropriations member Frank Wolf of Virginia procured $1.5 million for a Task Force on the United Nations to recommend much-needed institutional reforms.

Flake has identified the single most effective pressure point to force U.N. cooperation. The United States has been the United Nations' biggest contributor since the latter was founded in 1945. In 2004, the U.S. contributed $360 million toward the U.N.'s routine operating expenses -- 22 percent of the U.N.'s regular annual operating budget and more than the combined contributions of France, Germany, China, Canada and Russia. (This figure excludes U.S. funding for peacekeeping operations, and contributions toward the global AIDS fund.)

Congressional leaders should go beyond the Flake proposal and make it clear that Congress will withhold all of the U.S. assessed contribution until the United Nations has provided unlimited access to relevant documentation and the sworn testimony of officials. U.N. officials accused of criminal activity should surrender diplomatic immunity and face prosecution. The withheld funds should be placed in an escrow account, with future disbursement contingent on these matters being satisfactorily resolved.

In linking the U.S. contribution to the U.N. to the scandal, congressional leaders would be aligning themselves with President Bush, who recently said, "It's very important for the U.N. to understand that there ought to be a full and fair and open accounting of the Oil for Food program. In order for the taxpayers of the U.S. to feel comfortable about supporting the U.N., there has to be an open accounting."

The U.N. owes its financial supporters the courtesy of full transparency and, ultimately, full accountability for any of its officials who breach this trust.

The Oil for Food scandal may well prove to be a watershed in U.N. history. With sufficient congressional pressure, the international outcry should force positive reforms on the U.N. Congress owes it to the American people to ensure the U.N. is held accountable for Saddam's massive manipulation of a humanitarian program established to help the people of Iraq. Withholding taxpayer funds will send a clear message to the bureaucrats in Turtle Bay that the U.N.'s future depends on its coming clean now.

Nile Gardiner is a fellow in Anglo-American security policy, and James Dean is deputy director of government relations, at The Heritage Foundation (heritage.org).