Baghdad, Iraq ? U.N. weapons experts headed into the Iraqi desert Wednesday to destroy their first batch of banned Iraqi weapons — 10 leftover artillery shells filled with caustic, lethal mustard gas.

The shells were found by previous U.N. inspectors in the 1990s but had not been destroyed by the time the monitoring program collapsed in 1998.

U.N. specialists, working with an Iraqi team, will take four or five days to eliminate the 155mm shells — the first banned armaments destroyed since inspectors returned to Iraq in November after a four-year hiatus.

As progress was reported in eliminating the leftover chemical weapons, the U.S. ambassador to the United Nations said international experts found that an Iraqi missile exceeded the maximum 93-mile range allowed under U.N. resolutions.

Ambassador John Negroponte told reporters at U.N. headquarters in New York that it was now up to chief weapons inspector Hans Blix to recommend what to do about the finding.

Blix refused to comment on Negroponte’s remarks, saying that he would mention the case to the U.N. Security Council on Friday when he and the head of the U.N. nuclear agency, Mohamed ElBaradei, report on the progress of Iraq’s disarmament.

International missile experts met Monday and Tuesday to examine Iraq’s production of the al-Samoud 2 and al-Fatah missiles, which in some tests exceeded the maximum range allowed under Security Council resolutions in place since the 1991 Gulf War.

“My understanding is that one of the two missiles that is being analyzed definitely has a capacity that exceeds the range of 150 kilometers (93 miles),” Negroponte said. “That is something that our own intelligence sources have been telling us for months. But apparently now it’s a matter of agreement among the experts.”

He identified the missile as the al-Samoud 2, a liquid-fueled missile that Iraq declared in its semiannual report to inspectors and in its 12,000-page weapons declaration on Dec. 7.