At a test site along the Euphrates River, U.N. weapons inspectors joined Iraqi specialists and observed a static test of an engine for the al-Samoud missile, an Iraqi weapon under close scrutiny by the international arms monitors.

Chief U.N. weapons inspector Hans Blix, in a report to the U.N. Security Council in New York on Monday, said flight tests of the al-Samoud had exceeded by about 20 percent the maximum range of 90 miles allowed for Iraqi missiles under U.N. resolutions that have limited Iraq's weapons programs since its defeat in the 1991 Gulf War.

Although a seeming violation, the missile's range required further study, said Blix, who discussed it with Iraqi officials during a Jan. 19-20 visit to Baghdad.

"We were told that the final range for both systems would be less than the permitted maximum range of 150 kilometers," he told the council.

Earlier Monday, the U.N. missile experts traveled to the al-Rafah site, 25 miles southwest of Baghdad, for the test firing of the engine.

American intelligence analysts had suggested last October that a new, larger al-Rafah test stand, a steel frame holding engines for test-firing, might be used for missiles with longer ranges than the 90 miles allowed under U.N. resolutions.

The inspectors, who first went to al-Rafah in November, have visited more than a dozen such sites targeted by U.S. and British intelligence, without reporting any violations. They reported no conclusions after Monday's test.

The U.N. inspection agency reported that other teams on Monday visited a naval complex 200 miles south of Baghdad, and a storage site just west of Baghdad, where they used a metal analyzer to check sheets of alloy.

Nuclear experts, meanwhile, conducted a radiation survey by vehicle in the al-Taji area, an industrial zone north of Baghdad. Detection of certain radioactive isotopes in the environment could signal prohibited work on nuclear weapons.

Since resuming inspections last Nov. 27, the U.N. monitors have made some 500 visits to more than 200 sites, to enforce U.N. prohibitions on chemical, biological and nuclear weapons programs.