Five National Broadcasting Co. officials have been fired or have resigned in connection with alleged embezzlement and kickback schemes involving falsified travel vouchers.

Federal prosecutors in Washington and New York believe the scheme may have been going on for a decade and may eventually involve more than 50 employes.

Those fired were Steve Weston, NBC vice president in charge of unit managers in New York; his deputy Bill Aulepp; and John Walsh director of unit managers in Washington. Carlyle Robinson and John Cox, who worked under Walsh, have resigned.

Unit managers who on the average earn between $30,000 and $40,000 a year, make the logistical arrangements for television correspondents and crews on location. They make reservations and handle the funds to pay for transportation, hotels, rental cars, meals and other travel expenses.

According to knowledgeable sources, some unit managers would order more tickets than necessary, then return the unused tickets and have the funds credited to their personal accounts with the travel agency. Or they would sell the unused tickets.

NBC took the unusual step of airing the story on its own network last Friday. Correspondent Carl Stern reported that managers traveling overseas were told to bring back such things as "jade, gold coins, fancy shoes, Oriental carpets and cash." He quoted federal authorities as estimating the amount involved in the alleged scheme at $100,000 in Washington alone.

Sources declined to state how much audits of the New York operation had uncovered, but one speculated the amount could reach $500000.

The broadcast also said the two employes tentatively agreed to plead guilty to federal fraud charges. Robinson's attorney, John Gill, denied that his client had made such an agreement. "Anything Mr. Robinson did," Gill added, "resulted from pressure from above in the organization." As one NBC source put it, "It was go along or be fired."

The source added that two of the unit managers had admitted to the prosecutor taking some of the money for themselves, however.

Another source close to the case said the pair had agreed in principle to plead guilty to a single count of fraud if the charge is a misdemeanor. The prosecutor is reportedly holding out for a felony charge. Patrick Moran, attorney for John Cox, said there had not yet been any resolution of the plea.

The alleged scheme was discovered in the Washington bureau last fall as the result of a tip. Walsh, a 30-year NBC veteran, and the two others, who had been network employes for many years, channeled their travel business through Executive World Travel. This firm, with offices on K Street and in the surrounding states, is wholly owned by the Marriott Corp.

The general manager of Executive World Travel, until his resignation last month, was Raiford S. Pierce. He was reached in Tampa, Fla., where he now works for a firm selling computers to travel agencies. Pierce said he handled travel arrangements for NBC's Washington bureau for about two years, and that the bureau gave him about $60,000 to $70,000 a year in business. "They were not even among my top 20 customers," he said.

Pierce, who insisted his resignation was not connected with the alleged scheme, said it was common for commercial clients to have personal accounts as well with the agency. He explained that executives need them to pay for family travel when members accompany them.

Pierce said he had only sparse dealings with the NBC trio of unit managers and that daily operations were handled by his staff of 42.He said he had informed the prosecutor of his impending move to Florida and that no charges have been filed against him.

Reached at his home in Maryland, John Walsh also said no charges had been filed against him. "No one knows what's happening," he added, referring to the ongoing investigation. Walsh was fired last fall.

NBC has its own in-house travel agency in New York. There Aulepp held the same position as Walsh in Washington, while Weston was in charge of unit managers in all NBC bureaus. Weston, who was fired in January, was said to have joined NBC in about 1966, although NBC public relations in New York refused to confirm this "because he is no longer an employe." The alleged scheme was said by one NBC source to date back to the 1968 political conventions.