UNITED NATIONS (Reuters) - On the day before it is due to be shut down, the U.N. unit that found no weapons of mass destruction in Iraq but failed to stop the U.S.-led invasion said on Thursday time had justified its methods and work.

In a voluminous report detailing the history of Iraq’s banned weapons programs and U.N. efforts to dismantle them, it said the episode had shown that on-the-ground inspections were better than intelligence assessments by individual countries.

The report by the U.N. Monitoring, Verification and Inspection Commission, or UNMOVIC, did not name its targets but several of its conclusions appeared aimed at the United States and Britain, which invaded Iraq in March 2003.

Washington and London said despite UNMOVIC’s inability to find evidence, they were acting in the belief that Iraq was pursuing chemical, biological and nuclear weapons programs begun in the 1970s. No such weapons have been found.

“Despite some skepticism from many areas within the international community, in hindsight, it has now become clear that the U.N. inspection system in Iraq was indeed successful to a large degree, in fulfilling its disarmament and monitoring obligations,” said the unit’s 1,160-page summing-up report.

“The UN’s verification experience in Iraq also illustrates that in-country verification, especially on-site inspections, generate more timely and accurate information than other outside sources such as national assessments.”

UNMOVIC was in Iraq only from November 2002 until it was pulled out on the eve of the invasion, but its predecessor, UNSCOM, spent seven years there scrapping Iraqi weapons of mass destruction and facilities after the first Gulf War of 1991.

On Friday, a U.S. and British-backed Security Council resolution is due to wind up UNMOVIC, which in recent years has been studying satellite photos and reporting on contaminated wreckage being sold abroad from former weapons plants.

PROVING A NEGATIVE

Before the 2003 invasion, UNMOVIC reports said they could not account for all of Iraq’s chemical and biological materials but could not prove that Baghdad resumed production of them.

The new report signed by UNMOVIC acting executive chairman Demetrius Perricos said it now seemed that much of what Iraq had said about its weapons in later years had been accurate.

But it said the government of late Iraqi leader Saddam Hussein had found itself trying to prove a negative, a situation it had brought on itself by previous years of lying.

“With false and misleading information being supplied by Iraq, particularly during the early years of the inspection process, it became almost impossible for Iraq to provide convincing evidence that would remove doubt that even more evidence remained undisclosed,” it said.

It said that during its brief stay in Iraq, UNMOVIC carried out 731 inspections covering 411 sites, but it implied that U.S. and British anxiety to invade Iraq had hampered its work.

“Had UNMOVIC not been under such a stringent time constraint, the inspections could have been more detailed and thorough and many issues which emerged could have been pursued to a conclusion allowing greater confidence in the inspection process,” it said.

Hans Blix, the Swede who headed UNMOVIC at the time, has been more outspoken.

“The U.S. and the U.K. chose to ignore (our reports) and to base their action upon their intelligence,” Blix said in a 2005 interview. “We didn’t want an invasion; we wanted inspections.”

In other sections, the report said UNMOVIC had found that from the mid-1970s to 1990, more than 200 foreign suppliers had provided Iraq with critical technology, equipment, items and materials used in banned weapons programs. U.N. officials said the report’s authors had decided not to name the suppliers.