ROME (AP) _ Italy ordered an investigation Friday into reports that two DC-9 airliners narrowly escaped collisions with military planes this week over the Mediterranean, where NATO is conducting maneuvers, authorities reported.

Both near-misses reported Wednesday involved domestic flights of ATI, a subsidiary of Alitalia, Italy's national airline. The government had begun discussing the safety of commercial air passengers during NATO maneuvers after a similar close call 20 days earlier.

Defense Minister Giovanni Spadolini said that no Italian military aircraft or foreign planes were taking part in NATO maneuvers ''at that moment'' Wednesday when the incidents occurred.

He said, however, that in the case of one of the flights - from Pisa to Palermo - ''the only aircraft that crossed the airspace at that time'' came from the French aircraft carrier Clemenceau. Spadolini said in a statement that the French plane later landed at the Sigonella air base outside Catania.

U.S. Navy Capt. James Mathews, spokesman for the Allied Forces Southern Europe, headquartered in Naples, said NATO was awaiting reports from air traffic controllers

''We're trying to sort out'' just which military craft may have been involved, he said.

Transportation Minister Claudio Signorile said he has ordered a probe into the reported near-misses.

He said a government commission charged with studying air safety in the Mediterranean has recommended such measures as preserving the tapes from the cockpit recorder aboard military flights in the area of commercial flights; and monitoring by radar all flights in areas where military maneuvers are under way.

Gen. Antonio Mura, head of an agency representing Italy's air traffic controllers, said French Etendard fighter bombers could have been involved, but all that was ''certainly'' known was that they were foreign military jets.

According to Italian newspaper reports, the pilot of an ATI jetliner bound from Rome to Cagliari, Sardinia, on Wednesday told air controllers as his craft flew over Sardinia: ''Two unidentified fighters just crossed us. They were 50 meters (160 feet) in front of us.''

The pilot of another ATI jetliner flying from Pisa to Palermo told the control tower in the Sicilian capital 51/2 hours later, ''We have seen an anti-submarine aircraft crossing our course,'' the reports said.

Rome's La Repubblica quoted the pilot, Paolo Palagi, as saying: ''I saw speeding under me, about 60 meters away, a military plane . ..''

NATO has been conducting the Distant Hammer exercise between Sardinia and Sicily, which are off Italy's western coast. U.S., Italian, British, French and Dutch troops and planes are participating in the operation.

On April 19, an ATI airliner reported a close call with a Tornado fighter jet over Falconara on Italy's east coast.