UNITED NATIONS -- The big U.S. chemical producer E.I. du Pont de Nemours & Co. and Leybold Vacuum Products Inc., the Pennsylvania subsidiary of the German engineering company Leybold AG, are among companies whose products were used in Iraq's covert nuclear weapons program, United Nations inspectors who have examined the equipment say.

A list of some 13 companies, most of them German, is being prepared by the International Atomic Energy Agency, the U.N. body charged with tracking down and destroying the secret Iraqi program.

It will be sent to Secretary General Javier Perez de Cuellar later this week along with the report of the eighth and most recent nuclear inspection team to visit Iraq.

Officials in Vienna say Hans Blix, the director of the atomic energy agency, is leaving it up to the secretary general to decide whether the list of involved companies should be published.

The agency does not accuse the companies on its list of deliberately and knowingly helping Iraq in its bid to become a nuclear power or even of supplying their products directly.

Clint Archer, a spokesman for du Pont at the corporation's headquarters in Wilmington, Del., said he could provide no details about the equipment other than to say it was made by a du Pont subsidiary.