Officials of American Telephone & Telegraph Co. destroyed a series of documents in 1974 that dealt with Bell System competitors, according to sworn testimony by an AT&T official.

The testimony was contained in a document filed by MCI Communications Corp. with the U.S. Court of Appeals in Chicago. The Bell employee's deposition is also in the hands of the Justice Department which is evaluating it in connection with its ongoing antitrust suit against AT&T, sources said.

According to the MCI document, the employee, Leigh Tripoli, who is still with the Bell System, said that AT&T "undertook a deliberate and widespread document-destruction effort" just before lawyers for MCI were to visit AT&T offices and that she saw "six or seven large wastebaskets being filled with documents from AT&T office files and taken away by trash collectors."

"She testified that numerous AT&T employees had been instructed to destroy any embarrassing documents dealing with specialized common carriers, interconnection or competition and any copies of documents with notes or memos written in the margins," MCI said.

"AT&T employees were told these documents were to be destroyed so that MCI attorneys, who were coming to look through AT&T's files, would not see them," MCI said.

An AT&T spokesman, Pickard Wagner, said the charge "is clearly not true. What MCI alleges was a misunderstanding on her part," he added. "However, even if it were true, and it isn't, the judge in the case ruled that it had nothing to do with the MCI case. It's simply an extraneous matter." iMCI Chairman William McGowan refused to comment.

According to the filing, Tripoli saw "many" AT&T employees destroy the documents, while others took documents home so they would not be available. tFurther, according to MCI, Tripoli said in a deposition that documents were destroyed in her presence. Tripoli worked in the department that "housed the business relations section which was responsible for dealing with MCI," the company said.

Although the deposition is under seal and U.S. District Judge John Grady refused to permit introduction of the documents in last year's trial of MCI's antitrust suit against AT&T, MCI revealed the thrust of the testimony in a cross appeal of the case. A jury awarded MCI a record $1.8 billion in the antitrust case and AT&T is appealing the decision.