WASHINGTON - President Bush ranked in the middle of his Air National Guard flight class and flew 336 hours in a fighter jet before letting his pilot status lapse and missing a key readiness drill in 1972, according to his flight records belatedly uncovered Tuesday under the Freedom of Information Act.

The Pentagon and Bush's campaign have claimed for months that all records detailing his fighter pilot career have been made public, but defense officials said they found two dozen new records detailing his training and flight logs after The Associated Press filed a lawsuit and submitted new requests under the public records law.

"Previous requests from other requesters for President Bush's Individual Flight Records did not lead to the discovery of these records because at the time President Bush left the service, flight records were subject to retention for only 24 months and we understood that neither the Air Force nor the Texas Air National Guard retained such records thereafter," the Pentagon told the AP.

"Out of an abundance of caution," the government "searched a file that had been preserved in spite of this policy" and found the Bush records, the letter said. "The Department of Defense regrets this oversight during the previous search efforts."

Bush's Vietnam-era service in the Texas Air National Guard has become an issue in the presidential campaign as the candidates spar over who would make the best commander in chief. Supporters of Democratic nominee John Kerry , a decorated Vietnam combat veteran, have criticized Bush for serving stateside in the National Guard. Kerry's Republican critics claim Kerry did not deserve some of his five medals.

Bush has repeatedly said he is proud of his Air National Guard service. White House spokesmen said as late as last week the administration knew of no other records of Bush's military service.

"These documents confirm that the president served honorably in the National Guard," White House spokeswoman Claire Buchan said Tuesday night.

Democratic National Committee communications director Jano Cabrera disagreed. "For months George Bush told the nation that all his military records were public," he said. "Now we know why Bush was trying so hard to withhold these records. When his nation asked him to be on call against possible surprise attacks, Bush wasn't there."

The newly released records show Bush, a lieutenant in the Texas Air National Guard, ranked No. 22 in a class of 53 pilots when he finished his flight training at Moody Air Force Base in Georgia in 1969.

Over the next three years, he logged 326.4 hours as a pilot and an additional 9.9 hours as a co-pilot, mostly in his the F-102A jet used to intercept enemy aircraft. Of the 278 hours he flew in the interceptor, about 77 hours were in the TF-102A, the two-seat trainer version of the one-seat fighter jet.

The records show his last flight was in April 1972, which is consistent with pay records indicating Bush had a large lapse of duty between April and October of that year. Bush has said he went to Alabama in 1972 to work on an unsuccessful Republican Senate campaign. Bush skipped a required medical exam that cost him his pilot's status in August of that year.

Bush's 2000 campaign suggested the future president skipped his medical exam in part because the F-102A was nearly obsolete. Records show Bush's Texas unit flew the F-102A until 1974 and used the jets as part of an air defense drill during 1972.

A six-month historical record of his 147th Fighter Interceptor Group, also turned over to the AP on Tuesday, shows some of the training Bush missed with his colleagues during that time.

Significantly, it showed the unit joined a "24-hour active alert mission to safeguard against surprise attack" in the southern United State beginning on Oct. 6, 1972, a time when Bush did not report for duty, according to his pay records.

Bush's lone service in October was outside Texas, presumably with an Alabama unit he had permission to train with in September, October and November 1972.

As part of the mission, the 147th kept two F-102a jets - the same Bush flew before he was grounded - on ready alert to be launched within five minutes' warning.

The records also show Bush made a grade of 88 on total airmanship and a perfect 100 for flying without navigational instruments, operating a T-38 System and studying applied aerodynamics. Other scores ranged from 89 in flight planning to 98 in aviation physiology.