Shortly after a CIA anti-drug team told the Peruvian Air Force about an unidentified plane over the Amazon jungle, the plane's flight pattern made the Americans question whether it was a drug plane, U.S. officials say.

The single-engine Cessna was flying straight, level and at a reasonably high altitude deep into Peru's air space instead of sticking low to the ground and near the border and taking evasive maneuvers, the officials said Wednesday. They spoke on condition of anonymity.

Despite the Americans' expressed uneasiness, and their expectation that the Peruvian fighter would make a concrete identification before attacking, the jet opened fire on the pontoon plane within minutes Friday night. American missionary Veronica ``Roni'' Bowers and her 7-month-old daughter were killed in the attack.

Bowers' husband, Jim, and their 6-year-old son, Cory, survived, as did pilot Kevin Donaldson, who was wounded and has undergone surgery on both legs.

Established procedures hold that Peruvian pilots whose fighters approach suspect planes verify the registration, use hand signals and radio messages to make contact, rock the jet's wings as a sign for the suspect plane to land and fire warning shots.

As U.S. officials see it, the incident was a departure from what they regard as a highly professional performance by the Peruvians in the anti-drug program.

``Nobody is saying the Peruvians aren't capable aviators,'' said CIA spokesman Bill Harlow. The drug interdiction program has been very successful over the last few years, and CIA crews have been ``impressed with the professionalism of the Peruvians. They've done a good job under sometimes dangerous circumstances. In this case, obviously, something went terribly wrong.''

A Peruvian liaison on each U.S. plane is responsible for relaying information to the Peruvian military about planes spotted by CIA surveillance crews. It was not immediately clear whether the liaison officer was aware of the crew's comments Friday suggesting the Cessna could be an innocent aircraft.

The CIA is transcribing audio and video tapes that could clear up the details, said Sen. Bob Graham, D-Fla., the Senate Intelligence Committee's top Democrat.

``We've been told this was a very complicated task of multiple persons talking in two languages in difficult circumstances, the loud airplane,'' Graham said Wednesday. ``They said they were still going through a laborious process of trying to get a transcript of the audio tape.''

A congressional aide familiar with the investigation said the Peruvian could have been speaking with his compatriots in the air or on the ground, or he could have been using an intercom system that blocks out the comments of others while he speaks.

Language should not have been a problem, despite the CIA crew's rudimentary Spanish skills, since the Peruvian on board is bilingual, following the practice in all such U.S. anti-drug flight programs in Latin America, including those run by the U.S. Customs Service, officials said.

``This guy's language capabilities were tested within days of this flight, and he passed that test,'' said an intelligence official who spoke on condition of anonymity.

The incident led to a suspension of the CIA program. A U.S. team is expected to fly to Lima soon to discuss ways to ensure Friday's downing will not be repeated. Officials say the suspension is expected to end in a few weeks.

State Department spokesman Philip Reeker said a similar program with Colombia also has been suspended. The programs have been in effect for more than a decade, save for a brief suspension in 1994 over unresolved legal issues.

In Bogota, Colombia's air force chief said the suspension of U.S. airborne surveillance cooperation over his country will hamper anti-narcotics efforts.

``This is serious for everybody, because it will permit drug traffickers to operate with a certain freedom,'' Air Force Gen. Hector Velasco told The Associated Press. He said he was told the suspension would be temporary.