Seventeen employes of People Express airlines were fired or asked to resign last week following the disappearance of $5,000 from a company safe at National Airport, the employes said yesterday.

Some of the workers said they were questioned about the missing money before being fired, but an airline spokesman said there was no connection between the occurrences.

A spokesman for the Federal Bureau of Investigation reported that it is looking into the theft.

People Express spokesman Ed Stukane said the employes were released for "not performing their jobs, and unprofessional behavior." He would not elaborate, and said the matter was "something between the company and former employes."

Several of the ex-workers said the airline has had financial problems and that their firings were part of a cost-reducing plan. Stukane said, however, the terminations were not due to any financial losses by the airline.

Although some of the former employes claimed they would be replaced by college students, Stukane said there have been no final decision made regarding hiring replacements and that the airline is reorganizing its operations at National.

Three former customer service managers -- Walter Fields, Arnold Huff and Pam Thomas -- said yesterday they were ordered to attend meetings Friday. They said they were told that if they did not attend, the company would fire them.

There they were questioned about their "attitude" toward the company and were later asked to resign or else be fired, along with two other managers, the three said. All of them had been with the company from one to five years.

While they were being questioned, Fields said, a flight arrived carrying ". . . managers to temporarily replace us. We were being questioned . . . and they already had people coming in to take our place."

On Saturday, when five of the ground-service technicians resigned in protest, all 12 of the airline's technicians at National were fired, several former employes said.