A missile defense test that was supposed to have included an attempted intercept of a long-range missile Friday has been delayed until December because of a technical problem, the general in charge said Tuesday.

Lieutenant General Henry Obering, head of the Missile Defense Agency, said the attempted intercept was postponed following the discovery of a flaw in a device designed to measure the interceptor missile's performance.

"I could have elected to go ahead and fire on Friday, but we had at least a 20 percent change that we would lose all data in a test," he told reporters.

"Even if it were successful, we don't want to do that because these tests are expensive," he said.

The flight tests cost about 80 to 100 million dollars apiece, officials have said.

The development of the mid-course missile defense system has been plagued by gaps in flight testing over the years due in part to breakdowns resulting from the sheer complexity of the system.

Obering, however, insisted that there have not been "major design flaws or major functional flaws" in the missile defense programs.

"The failures were a component broke or if this particular component had a malfunction that we had to replace, but we have not had any major show-stoppers in our overall program," he said.

The latest problem is a device in the interceptor missile used only in tests that is designed to gather all its telemetry data.

He said all the devices produced have the same flaw, and it could not be fixed in time for Friday's test.

Obering said a test will still be conducted Friday only without the interceptor missile. A variety of sea- and ground-based targeting radars will track a long range target missile but the intercept will be simulated.

In December, the full test will be repeated with the interceptor missile, he said.

Friday's test was to have been the first since 2002 to involve a target missile with counter-measures such as a decoy balloon.