The commander of the Philippine Air Force admitted today that fighter planes were ordered into the skies over the capital about the time that opposition leader Benigno Aquino was flying into Manila International Airport on Aug. 21, 1983, but he denied that the action had anything to do with Aquino's ill-fated arrival.

Maj. Gen. Vicente Piccio charged that a U.S. Air Force logbook entry on the "scrambling" of Philippine fighters that day had been "doctored" to indicate that the planes were intended to intercept the jetliner carrying Aquino home from three years of exile in the United States and divert it to an air base north of Manila.

Aquino, the political archrival of President Ferdinand Marcos, was assassinated seconds after military guards escorted him off a Taiwanese China Airlines airliner. Twenty-five military men and one civilian are on trail in connection with the slaying.

Piccio was reacting to efforts by lawyers prosecuting the Aquino murder case to show the existence of a military conspiracy in the assassination. The lawyers raised the issue of the Air Force scramble after the San Francisco Examiner reported last month that two Philippine F5 fighters unsuccessfully tried to intercept Aquino's plane and divert it to Basa Air Base northeast of Manila.

The report quoted U.S. Air Force personnel as saying Philippine officers took over U.S. radar scopes at Wallace Air Station about 200 miles north of Manila to keep track of their scrambled fighters. It said they asked American officers to order U.S. jets into the air as well, a request that was denied.

A U.S. airman said a Philippine colonel later told him the jets were trying to divert the China Airlines plane to Basa, 35 miles northeast of Manila, but failed to intercept it.

Piccio denied the report last month as "just a sensationalized barracks story of the usual type bandied about in Air Force operations rooms." His admission today that the scramble took place came after the U.S. Embassy turned over to the Foreign Ministry a copy of a U.S. Air Force logbook entry.

According to a press release from the presidential palace, Piccio said "certain quarters" had attempted to "doctor" the logbook to link the scramble to Aquino's incoming flight. He did not indicate who was responsible.

The log entry said the Philippine Air Force major in charge at Wallace Air Station had informed U.S. personnel that the Philippine Air Force was directed by the control room at Villamor Air Base "to scramble and have rpc 1964 (aircraft inbound from Hong Kong) land at basa a.b. whether or not that is their intention. (Aquino)."

Piccio said the words in parentheses were written in different handwriting than the rest of the entry and inserted "after the logbook was written." A U.S. official said only the name "Aquino" appeared not to have been written by the same person who wrote the rest of the entry, but that it was not known when or by whom the name was inserted.

The "rpc 1964" and reference to Hong Kong were not explained. The plane carrying Aquino came directly from Taiwan.

Western diplomats said the logbook entry and Piccio's statement raise questions of why the aircraft were scrambled and why the action initially was denied.