BERLIN (AP) _ Pan American World Airways on Thursday disputed a U.S. media report that the airline's security was lax at Frankfurt Airport even after the bombing of Flight 103.

''All I can say is that we have a security staff that uses the most modern methods,'' said airline spokesman Harald Kosel from his office in West Berlin.

''Passengers are also matched up with their luggage, and are given a list of questions to answer, including where they came from, whether they packed their luggage themselves, and so forth, and their passports are checked against their tickets,'' Kosel said.

Asked if luggage brought on board by crew members also was checked, Kosel said: ''Yes, of course, everyone is checked.''

Kosel said the security staff was part of a Pan Am subsidiary called ''Alert.''

ABC World News Tonight on Wednesday alleged that baggage handlers and others at London's Heathrow Airport were not given a thorough background check, and that at least one Pan Am security guard in Frankfurt said he had received only minimal training before going to work for the company.

The ABC report came three weeks and a day after a bomb destroyed Pan Am Flight 103 over Lockerbie, Scotland on Dec. 21. All 259 people aboard the plane and at least 11 on the ground were killed.

Investigators are trying to learn who placed the explosives aboard the airplane, and where. The New York-bound flight began at Frankfurt and changed planes in London.

Kosel said, ''It appears now 99.9 percent sure that this didn't happen in Frankfurt.''

British investigators have said the explosives ruptured the fuselage of the Boeing 747 in the area of the cargo hold just forward of the plane's left wing.

They have also said they suspect the bomb used was an explosive produced in Czechoslovakia called Semtex. Czech officials have agreed to send experts to Britain to assist in the investigation.