Serbian aircraft were reported to have committed their first combat violation of the ban two weeks ago by bombing two Muslim villages.

Another is whether they were killed by allied planes or by Serbian artillery or even Serbian aircraft.

Air power, for example, might have been used, not just against Croatian airfields but also against Serbian aircraft and the artillery moving on Bihac.

Finally, Serbian aircraft have been used effectively as "weapons of intimidation" to strafe and bomb civilian centers, Administration officials said.

On Aug. 28, there was a near collision when a Serbian aircraft passed in front of a French relief plane, officials say.

According to a Pentagon official, the last instance of a relief plane being shadowed by Serbian aircraft occurred on Aug. 31.

That could eventually lead to allied combat planes threatening to shoot down Serbian aircraft defying the ban.

Serbian aircraft violate the U.N. resolution, and no one does anything.

Germany, Croatia's leading supporter, has banned Serbian aircraft and trucks from crossing into its territory.

"False stories are being spread in order to provoke international forces into attacking Serbian aircraft," the statement said.