An Italian judge today stirred new controversy about a 1980 airliner crash off Sicily's coast by endorsing a theory that the plane's 81 passengers lost their lives in a dogfight between a Libyan fighter and NATO jets that he said has been hushed up for nearly two decades.

Judge Rosario Priore indicted four Italian generals for withholding information about the incident, alleging they had committed high treason and other crimes while hiding evidence that U.S. and French military jets were in the area when the plane went down. But he did not pinpoint any responsibility for the crash.

Five other military officials were accused of lying when they denied any role in the military activity, which Priore said must have been authorized by senior Italian or NATO officials. But several of the generals ridiculed the charges at a news conference. One said the report, which stemmed in part from disclosures made by NATO, was "based on incomplete data from an obsolete [radar] system."

The nine people indicted by the judge include the top air force officer at the time of the crash, Lamberto Bertolucci; his deputy, Franco Ferri; air force department head Corrardo Melillo; and intelligence chief Zeno Tascio. NATO officials sought to keep a low profile today by branding the controversy an Italian matter.

If U.S. planes were involved, the incident could add to public concerns about the presence of NATO bases in Italy. Those concerns stem partly from the severing of a cable car wire by a U.S. Marine Corps jet in northern Italy in February 1998, killing 20 people, and partly from NATO's bombing of Yugoslavia this spring in a war that was unpopular here. Italian bases played a central role in the air campaign.

The DC-9, flying a southwesterly route on a path from Bologna to Palermo, disappeared from radar screens the evening of June 27, 1980, and plunged into the Tyrrhenian Sea, giving rise to speculation about the cause. According to the Italian news agency ANSA, Priore concluded in a lengthy report on his investigation that at least six fighter aircraft were in the vicinity at the time, two French planes from a base in Corsica and four U.S. planes, including two Corsair jets and two jets from an aircraft carrier.

The shards of a Libyan jet were found on a mountain in Calabria, in southern Italy, three weeks later, and Italian officials claimed the crash had occurred then. But Priore said he has reason to believe that the Libyan jet was downed at the time of the commercial airliner crash. The DC-9 "absolutely was not alone, [and] neither was the sky . . . totally empty for a range of 50 miles," ANSA quoted Priore as saying in the report.

Walter Veltroni, a leader of the principal party in Italy's governing coalition, called on NATO members and officials to release additional information that would clear up the mystery.

Previous inquiry panels have found evidence of both a bomb explosion aboard the aircraft and a missile attack. The continuing speculation into the cause has been one of Italy's lasting mysteries, inspiring a book and a movie.

French, U.S. and NATO officials have long denied any military activity in the skies that night. Libyan leader Moammar Gadhafi has blamed the United States for the airliner's crash but offered no evidence.