WASHINGTON (Reuters) - A missile that the U.S. military hopes will be part of the Bush administration's controversial missile defense program failed to intercept its target during a test on Saturday, the U.S. Army said.

The upgraded Patriot PAC-3 missile, made by Lockheed Martin Corp., was supposed to intercept a cruise missile target in Saturday's test in New Mexico.

Two other older Raytheon Co. PAC-2 missiles also were launched as part of Saturday's test. The Army said only one of the two missiles scored a successful hit, destroying a drone aircraft.

The "hit-to-kill" missiles, advanced versions of the Patriot anti-aircraft missile used against Iraqi Scud missiles in the 1991 Gulf War, are designed to collide with their targets in flight at high speed.

But opponents of the anti-missile system have argued that technological problems could prevent the program from becoming a viable defense system for the United States.

The Bush administration hopes the system eventually will shield American cities, as well as U.S. troops and overseas bases, from missile attack.

Saturday's test was designed to simultaneously shoot down a remote-controlled QF-4 "Phantom" fighter jet, a cruise missile and a smaller drone aircraft. This first operational test followed 11 successful developmental flight tests.

The next test has not yet been scheduled, but the military is hoping to complete the current round of four tests on the PAC-3 system by May.

The PAC-3 missile tested on Saturday is designed to provide upgraded defenses against modern battlefield ballistic missiles, cruise missiles and aircraft.

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