A contentious United Nations (search) debate is brewing — and this time it's not over Iraq. It's all about who pays to maintain the U.N. itself.

The U.N.'s two 50-year-old buildings in New York City are basically falling apart — decaying pipes and crumbling ceilings are now commonplace — and the U.N. is seeking an interest-free loan worth more than $1 billion to renovate its headquarters.

Who will pay to fix the 1952 original plumbing, get rid of asbestos and raise security fences? Repairs would cost U.S. taxpayers about $600 million over 30 years.

Critics want the U.N. to pay for the renovation itself.

The sour economy means Americans are not exactly in the giving mood. That, along with the U.N.'s foot-dragging over the war in Iraq, has sparked outrage.

"It is irrational, it is simply just looking to the United States to pay that which we should not have to pay," Leo Kayser III, former director of the U.N. Development Corporation (search), said. "We have no commitment, there is no legal basis for it."

And the problems go far beyond the need for a new paint job. Jon Clarkson, program director of the capital master plan, pointed out that dangerous materials are being inhaled by everyone in the buildings.

"Air-handling units provide heating and air conditioning for the office building," he said. "There are 3,000 air-handling units [which have] asbestos and hazardous materials behind them."

And it's not just asbestos. There are no firewalls or sprinklers — a violation of current building codes. And the heating and steam systems dating to the 1950s are on the verge of collapse.

Toshiyuki Niwa, who is leading the renovation project, said the U.N. wants to borrow $1.2 billion for the repairs. And he wants the United States to put up the cash.

The U.N. would repay the principal on the loan over 30 years, leaving Americans to pay the interest — some half a billion dollars' worth.

"It is an established norm set by the host countries following the example set by the U.S. government after World War II to provide an interest-free loan," Niwa said.

The United States already writes a much heftier check to fund the U.N. than any other country.

The General Assembly (search) decided that the U.N. should not rely more on one member to finance its operations than another, and established a "ceiling" rate, setting the highest amount any country is assessed, according to the State Department (search).

The Assembly revised the scale of assessments in 2002. As part of that agreement, the regular budget maximum was reduced from 25 to 22 percent — the rate at which the U.S. is assessed for the regular budget.

The U.S. is the only member that pays this rate; all other members’ assessment rates are lower. For example, Japan, Italy and Canada contributed, respectively, 19.6 percent, 5.1 percent and 2.6 percent to the regular U.N. budget for 2001, according to the State Department.

President Bush now has to decide whether to request the interest-free loan in the fiscal budget for 2005. And then Congress has to decide for the American people whether to fortify the U.N. or to let it whither on the vine.

Fox News' Amy C. Sims contributed to this report.