The Defense Department confirmed yesterday that four of its F15 fighters were at the wrong altitude Oct. 30 when they came within an estimated 100 feet f a Concorde supersonic jet transport flying east of Ocean City.

The incident first was reported to the Federal Aviation Administration by the pilot of the Air France Concorde flight, which had left Dulles International Airport en route to Paris. According to the FAA, the Concorde carried 16 passengers and a crew of nine.

Thomas Ross, a Pentagon spokesman, said yesterday that "our planes were at the wrong altitude." That was a change in the Pentagon's earlier position, when Ross said that the F15s were "where they were supposed to be." The fighters were on refueling training mission with another plane, a KC135 tanker.

Ross said yesterday that he had first spoken on the basis of incorrect information given to him.

FAA spokesman Fred Farrar said yesterday that the incident occured about 2:30 p.m. Oct. 30 about 60 miles east of Ocean City, before the Concorde had entered supersonic flight.

The Air France jet was at an altitude of 28,000 feet.

A military training area exists at that point between 29,000 and 31,000 feet and therefore is off limits to other aircraft without special permission.

The Air France pilot requested a higher altitude than 28,000, but the request was not granted while the New York City air traffic controller checked with the Tactical Air Command, Farrar said. Before the controller could gain permission or denial for the higher altitude assignment, the Concorde pilot reported the "near-miss," and estimated the distance at 100 feet.

In rechecking tapes of air traffic control data, the FAA found that the four F15s were at 27,200 feet at the time of the incident, Farrar said. "Our determination is that they [the F15s] came out of their assigned airspace," Farrar said.

There has been a considerable controversy over the years about whether military aircraft actually remain in their assigned blocks of airspace. wMany complaints have been filed by both controllers and pilots charging that military pilots regularly enter civilian airspace without proper clearances or warnings.