WASHINGTON (AP) _ While new government accident statistics show 1984 to be one of the safest for major airlines, the Federal Aviation Administration is acknowledging that some near collisions went unreported in recent years.

FAA spokesman Edmund Pinto confirmed Thursday night that reports of some near in-flight collisions were never sent to Washington and, therefore, weren't included in annual statistics.

Pinto did not provide any specific numbers of unreported incidents, saying the total was less than 3 percent.

But ABC News reported Thursday that at least 102 near in-flight collisions had been confirmed during 1983 and 1984 and were unaccounted for in the FAA's figures. The agency's statistics claim to show a sharp reduction in such incidents during recent years.

The report came as the National Transportation Safety Board issued statistics showing that major commercial airlines and general aviation aircraft improved their safety records in 1984. The fatality rate of commuter airlines, however, doubled last year over 1983, their safest year, the NTSB said.

ABC said the uncounted near-misses included 63 reports to the FAA by pilots when their aircraft came within 500 feet of other planes.

The FAA also did not include numerous reports of ''operational errors'' by controllers that were never counted although the incidents met the agency's criteria for near collisions.

Pinto said FAA administrator Donald Engen was first made aware of the uncounted incidents by ABC and shortly thereafter ordered changes in the agency's reporting procedures to ensure that those and any others were sent to Washington.

Pinto said the problems with reporting procedures have ''been going for years.'' Once Engen was made aware of the unreported incidents, he ''corrected the system.'' ''It's a paperwork and accounting problem,'' Pinto said.

The spokesman disputed suggestions that ''a slip in sending paperwork to Washington'' showed that near collisions were not being reduced.

Roughly the same number of near collisions went unreported over recent years. Therefore, ''the trend remains the same,'' Pinto said.

Last October, the FAA reported that the number of close calls had dropped from 568 in 1980 to 286 in 1983. At the time, the FAA said 142 near collisions were reported during the first eight months of 1984.

Meanwhile, the NTSB figures showed that 1,098 people were killed in airplane accidents last year, of which 998 involved general aviation aircraft. The agency noted that 1984 marked the first year that general aviation deaths fell below 1,000.

There were 12 accidents - about one for every 450,000 scheduled departures - involving the U.S. airlines that fly large jet aircraft, the best record since 1980 when those airlines recorded a fatality-free year of flying.

The only large jet accident to result in fatalities was the crash of a Zantop International Airlines cargo plane in Pennsylvania. Four people were killed.

But the fatal accident rate more than doubled for commuter carriers in 1984 after they had their safest year ever in 1983. There were six fatal accidents and 60 deaths involving commuters during the year, a rate of 0.22 per 100,000 departures compared to 0.09 per 100,000 departures in 1983.

Nevertheless, the commuters' safety record still was better than it was in 1982 when the commuters' fatal accident rate stood at 0.25 per 100,000 departures.

NTSB Chairman Jim Burnett said the overall safety figures for 1984 reflected progress in maintaining a safe airway system.

''Overall, I think we've made progress, but the 1,098 people that we lost were lives that did not need to be lost,'' Burnett said in an interview.

He called the decline in general aviation fatalities ''a very significant thing'' and said that although the death rate from commuter accidents was up sharply from 1983, the commuters still ''had one of their best years in history.''

The commuter accidents included an aerial collision in August of a Wings West aircraft and a private plane near San Luis Obispo, Calif., that killed 17 people; the crash of a Viques Air Link plane in Puerto Rico, also in August, that killed nine people; and the crash of a Provincetown-B oston Airline plane that killed 13 people in December near Jacksonville, Fla.,