The Air Force yesterday approved layoffs of up to 10 days for 84,000 employees of its Logistics Command and warned union leaders that further furloughs may be in the works because of budget cuts.

"Massive furloughs within the Air Force will occur because of inadequate funds," the American Federation of Government Employees said. Cuts in the Strategic Air Command and Air Training Command are under consideration, according to the union. Spokesmen for the two commands said any plans for furloughs are up in the air.

The layoff authority granted yesterday comes early in the governmentwide effort to reduce spending to levels authorized in the omnibus appropriations bill signed into law in December.

Air Force leaders have delegated decisions on layoffs to major commands, where decisions are in the works, according to an Air Force spokesman.

The spokesman said "rumors are abundant," but only the Logistics Command has formally requested authority to lay off workers toward cuts of $1.7 billion in operations and maintenance accounts.

Fourteen members of Congress yesterday asked Gen. Alfred B. Hansen, head of the Logistics Command, for a briefing on the scope and rationale of the decision.

Rep. Richard B. Ray (D-Ga.) said there is little Congress can do. "It is just a money situation. The Air Force opted to go forward with the modernization of its weapons and equipment at the expense of personnel.

"I believe very strongly in logistics," said Ray, who represents Robins Air Force Base. "If logistics doesn't work, nothing else much works. It keeps the conventional forces we have already bought and paid for going."

A spokeswoman for the Strategic Air Command said "funding is not finalized . . . and therefore at the present time we do not have plans to implement a furlough." SAC, which commands the ocean-spanning missiles and bombers, has 108,577 military and 18,963 civilian personnel.

The Air Training Command, headquartered in Texas, announced late yesterday that it would institute a hiring freeze and terminate all temporary employees on Feb. 29. Officials are "still looking at ways to effect some savings, including the possibility of a furlough," a spokesman said. The Training Command, which trains pilots, mechanics, air traffic controllers and others, has 51,955 military and 12,679 civilian personnel.

A hiring freeze was installed last year in the Logistics Command, headquartered at Wright-Patterson Air Force Base in Ohio, and an early retirement option has been offered workers to reduce the workforce by attrition.

Hansen, in a letter to Congress, said he planned to cut overtime and let go 2,000 temporary employees by March.

Workers at Wright-Patterson expressed relief yesterday that temporary layoffs had been chosen over firings.

Firings, or reductions in force (RIFs), are expensive because the average worker is entitled to some severance pay. One House committee aide estimated that a RIF at the logistics command might cost as much as one-third to one-half a year's pay for each worker.

A spokesman for the Logistics Command said that the reason civilians and not uniformed personnel were being laid off was because the military is paid from separate accounts, which were not cut back.