Every weekday, at a secure commercial office building on Manhattan's East Side, a team of 20 U.N. experts on chemical and biological weapons pores over satellite images of former Iraqi weapons sites. They scour the international news media for stories on Hussein's deadly arsenal.

They consult foreign intelligence agencies on the status of Iraqi weapons. And they maintain a cadre of about 300 weapons experts from 50 countries and prepare them for inspections in Iraq -- inspections they will almost certainly never conduct, in search of weapons that few believe exist.

The inspectors acknowledge that their chief task -- disarming Iraq -- was largely fulfilled long ago. But, they say, their masters at the U.N. Security Council have been unable to agree to either shut down their effort or revise their mandate to make their work more relevant.

Russia insists that Iraq's disarmament must be formally confirmed by the inspectors, while the United States vehemently opposes a U.N. role in Iraq, saying coalition inspectors have already done the job.

"I recognize this is unhealthy," said Dimitri Perricos, a Greek weapons expert who runs the team, known as the U.N. Monitoring, Verification and Inspection Commission (UNMOVIC), and manages its $10 million annual budget. But, he added, "we are not the ones who are holding the purse; the one who is holding the purse is the council."

There was a time when the work of U.N. weapons inspectors on Iraq was the stuff of front-page news and impassioned speeches by world leaders. President Bush even argued that Hussein's refusal to cooperate with U.N. inspectors offered legal backing for the 2003 invasion.

But the inspectors' primary mission -- ridding Hussein's regime of chemical, biological and nuclear weapons -- has become irrelevant since a U.S.-led coalition toppled the Iraqi leader and discovered that his government had destroyed its most lethal weapons shortly after the 1991 Persian Gulf War.

"The reality on the ground is there is no WMD there," said Charles Duelfer, a former U.N. weapons inspector who published the landmark 2004 report of the CIA-led Iraq Survey Group, which concluded that Iraq's weapons had been destroyed. "I think they understand the distance their work is from reality."

But Perricos insists that the U.N. inspectors' work remains relevant and that some of Iraq's chemical and biological weapons could be reconstituted by insurgents, terrorists or even a future Iraqi government.

"Look, Iraq is not Denmark," he said. "They've made botulin, anthrax, VX, sarin; they've made the whole spectrum of horrifying items, and they've used them. We don't know how things are going to develop in the region, and we want to be sure there are some controls."

Last month, Perricos showed the U.N. commission's board satellite imagery of plundered Iraqi chemical factories that produce chlorine, which has been used by Iraqi insurgents in chlorine-bomb suicide attacks. He warned that insurgents may obtain more deadly chemical weapons on the black market, according to U.N. officials.

The U.N. inspection program also stands as a poignant reminder of U.S. intelligence blunders in Iraq and the U.S. failure to secure Iraq's sensitive industrial facilities after the invasion.

The commission's prewar assessment -- that there was insufficient evidence to prove that Baghdad had resumed production of weapons of mass destruction -- flatly contradicted U.S. claims at the time and has long since been vindicated.

The United States and Britain have recently mounted a concerted push to shut down the commission. Zalmay Khalilzad, the U.S. ambassador to the United Nations, introduced a resolution last month that would end the inspections.

"The U.S. position for years with UNMOVIC has been 'Been there, done that,' " said a senior U.S. official who monitors the commission, speaking on the condition of anonymity.

But Russia has resisted U.S. pressure. A senior Russian official who tracks the group's work said the U.N. inspectors -- not the U.S.-led coalition in Iraq -- must have the final say on whether Iraq has been disarmed.

And the inspectors say they cannot confirm Iraq's disarmament without access to the classified reports of the Iraq Survey Group and a final visit to Iraq to verify U.S. claims. The United States has refused U.N. requests for such information, Perricos said.

Hans Blix, the retired Swedish diplomat who led the U.N. commission before the U.S.-led invasion, said keeping weapons experts in the U.N. system could help train a new generation of inspectors who may be called on to investigate weapons programs anywhere in the world.

"The main part of the job is done," Blix said. "But there is a valuable asset that has stood the test and could be of great use in other areas," he added, noting that no international body conducts missile or biological weapons inspections.

That asset, however, may be losing some value. Many top inspectors left the agency after the fall of Hussein, returning to government posts or taking jobs elsewhere in the United Nations.

Some who remain have begun searching for other positions. "There are limited opportunities within the U.N. system" for people steeped in the arcana of Iraqi weapons, observed commission spokesman Ewen Buchanan, who is also looking for a new job.

Meanwhile, the commission's budget reserves -- financed by Iraqi oil revenue and valued at more than $300 million when the last U.N. inspectors left Iraq in March 2003 -- are shrinking.

More than $200 million has been returned to Iraq, and the Iraqi government made a formal request to the Security Council in April to terminate the commission and return its remaining $63 million to Iraq.

"This is really absurd. We're approaching five years now of this exercise in futility," said Feisal Amin al-Istrabadi, Iraq's deputy permanent representative to the United Nations.

Carne Ross, a former British diplomat who helped draft the 1999 resolution creating the U.N. commission, agrees. "The reason for them disappeared the day Baghdad fell," he said.

But even Ross regards UNMOVIC with nostalgia. He came up with the name one night by tossing cards with the words "commission," "verification," "observation," "inspection" and "monitoring" on a table and rearranging them until he found the least clumsy acronym.

"It doesn't exactly trip off the tongue," Ross said, "but it's my piece of history, and I'm clinging to it."