Defense Secretary Caspar W. Weinberger has deferred any purchases of the Air Force's air-to-air missile of the future and has suggested he might cancel the program unless cost growth can be contained, according to a Pentagon memo.

Weinberger's action on the projected $10.8 billion program is one of the harshest he has taken regarding a weapon in the past four years. As with his decision to postpone buying the Army's troubled Divad air defense gun last year, however, Weinberger left open the possibility of continued production if problems can be fixed.

The advanced medium-range air-to-air missile (AMRAAM) is intended to be the supermissile of the 1990s for Navy and Air Force pilots, a weapon that can be fired from a jet fighter and find and destroy an enemy plane by itself. But estimated AMRAAM costs have more than doubled since 1981 -- with each missile now projected to cost more than $400,000 -- and show no sign of slowing down, according to defense officials.

Two maverick civilian analysts working for the Air Force, A. Ernest Fitzgerald and Thomas S. Amlie, warned more than a year ago that AMRAAM was heading for "disaster," but Air Force leaders denied the problems were that serious. The Air Force, which has called AMRAAM essential to its future combat ability, asked Congress last year for more than $400 million for AMRAAM, less than half of which was funded.

Weinberger met with Air Force Secretary Verne Orr and Navy Secretary John F. Lehman Jr. last week and then decided to postpone any procurement at least until summer. His decision is explained in a memo signed on Monday by Deputy Secretary William Howard Taft IV, who attended the meeting, and sent to Orr and Lehman.

Taft's memo, obtained yesterday by The Washington Post, says that "comprehensive cost control actions must be undertaken immediately." It orders an Air Force-Navy committee "to consider the feasibility of actions outside the scope of the AMRAAM program that might yield a more cost-effective solution to the military requirement," meaning the purchase of a different weapon.

"I recognize that any delay in the start of missile procurement is accompanied by cost increases due to inflation," Taft wrote. "It is therefore my sincere hope that the task force put in motion by this direction is able to yield positive results in time for an AMRAAM program decision this summer."

AMRAAM's manufacturer, California-based Hughes Aircraft Co., is recovering from a spate of bad news last summer. The Air Force and Navy recently resumed monthly payments to Hughes for several other weapons, including the Air Force Maverick missile and the Navy Phoenix missile, after finding serious quality control problems in the company's Tucson plant.

A spokesman for Hughes last night said that he had not seen Taft's memo and could not comment on it. Air Force officials also declined comment.

The Defense Department initially estimated that AMRAAM would cost about $4.8 billion, but by last fall increased its estimate to $10.8 billion, which is supposed to buy about 24,500 missiles.

Some critics have said that AMRAAM's troubles reflect the Air Force's fascination with technology so sophisticated it is bound to fail. The all-weather, all-night missiles are supposed to home in on enemy planes with their own radars, allowing one pilot to destroy numerous enemy planes without putting himself in danger.