The Federal Aviation Administration is investigating charges of alcohol and drug use by employes at Provincetown Boston Airlines, a commuter carrier.

The investigation began after CBS News quoted an unidentified former employe of PBA as saying that the airline had both a drug and alcohol problem among its employes, including pilots.

"We started the investigation after the CBS report," FAA spokesman Ed Pinto said. "We regard the allegations as serious, even if they are anonymous."

The FAA has promised anonymity to the individuals who talked to CBS, he said, to encourage them to come forward. Pinto said it is not accurate, as earlier reported, that the FAA had been checking similar allegations for about a month.

In Naples, Fla., PBA's headquarters, airline officials met with Drug Enforcement Administration agents yesterday to discuss the issue, United Press International reported. Frank Chellino, a DEA spokesman, said after the meeting that the agency was not sure an investigation was required but that the DEA would coordinate its efforts with the FAA.

He said the DEA's main concern would be allegations that PBA pilots also were engaged in drug trafficking.

PBA spokesman George Kean said the airline will cooperate fully with any investigation, but expressed skepticism that the charges would prove true. "What we've got here is a phantom finger-pointer," he said.

In the CBS broadcast, an individual identified as a former PBA employe said, "There's many people there who come into work and they're legally drunk."

PBA has had two fatal accidents in the past year. A passenger was killed Sept. 7 when a PBA plane crashed and burned in Naples; all 13 people on board another flight were killed Dec. 6 when the plane crashed after takeoff from Jacksonville. There is no evidence of drug or alcohol abuse in either accident, according to the National Transportation Safety Board.