Sometime in 1979, William P. Masselli, whom authorities have labeled as a member of a New York Mafia family, was chatting with his son, Nat--a conversation that FBI agents dutifully recorded under a secret court order.

The senior Masselli was recalling an invitation he had received to fly with "Ronnie Schiavone and Ray Donovan" to some function for which a friend had extra tickets. Masselli indicated that he decided to drive instead, but was glad he went to the affair, since it gave him a chance to boost his trucking company, Jopel Construction.

"Good thing we went," Masselli told his son. "There were a lot of guys I don't even know. They say, 'I hear Jopel, Jopel it's a phantom outfit' . . . . 'That's us,' I says. . . . You'd be surprised the advertisement that does, you know."

The episode appears to raise new questions about the Senate confirmation hearings last January on Raymond J. Donovan's nomination as secretary of labor and about the thoroughness of the FBI's investigation into his background. Donovan is now under a new FBI inquiry as a result of fresh allegations concerning his conduct as a construction company executive in the 1970s.

During his confirmation hearings, Donovan was questioned repeatedly about the extent of his contacts with Masselli and Jopel Construction and Trucking, a multimillion-dollar-a-year subcontractor on New York City subway projects for Donovan's company, Schiavone Construction.

The FBI said its New York office had developed information that Schiavone Construction was "mobbed up." One informant said Schiavone's ties to organized crime stemmed from its contacts with Jopel Construction and Masselli, "an alleged self-admitted 'soldier' in an organized-crime group."

"This source alleges that Mr. Donovan is acquainted with organized-crime figures through Masselli on a business and social basis," the FBI reported Jan. 23. FBI officials said, however, that they had not been able to corroborate the claims and "found nothing there that warranted further inquiry in connection with this investigation."

Senate Labor Committee Chairman Orrin G. Hatch (R-Utah) raised the issue with Donovan Jan. 27.

Hatch: "How many total contacts have you had with . . . Masselli?"

Donovan: "I have searched my mind on that. It can't be more than three times that I have ever seen Masselli in my life. They were in passing, on the job site. The man is our subcontractor. So I would say three times would be accurate."

Hatch: "Have they been on a close or a social basis or more a contract business basis?"

Donovan: "Totally on a contract business basis."

Hatch: "You don't know him personally or socially at all other than you've met him in contract work?"

Donovan: "That's correct."

The government's Masselli tapes were compiled over seven months in 1979 as a result of the court-authorized monitoring of a South Bronx warehouse that serves as headquarters for Jopel Construction and a wholesale meat company that Masselli also runs. The conversation mentioning Donovan and Ronald Schiavone, however, was not reported to Capitol Hill until this summer, after Hatch and Sen. Edward M. Kennedy (D-Mass.) expressed chagrin to the FBI over press reports concerning the eavesdropping.

FBI Executive Assistant Director Lee Colwell, acting for Director William H. Webster, told the two senators July 6 that no conversation between Masselli and Donovan had been picked up. He also disclosed the conversation between Masselli and his son Nat, without dating it. Colwell said it was not "surprising or particularly significant" since Jopel and Schiavone did business together.

Evidently dissatisfied, the senators wrote back, asking why the FBI had not informed them of the conversation during the confirmation process and calling for more details about it and any other overhearings or references on the Masselli tapes "to other Schiavone officials."

In a final reply Aug. 10, Webster repeated that the conversation was not considered significant or surprising. But he said the other questions--about what kind of affair Masselli had attended and who invited him on the plane ride with Donovan, as well as what other references to Schiavone officials might exist--could not be answered because this would "violate . . . protective court orders."

Masselli at the time was under double indictment, accused in one case of "a pattern of racketeering" that included highjacking truckloads of food, and in another of conspiring to manufacture $100 million worth of "synthetic cocaine." He pleaded guilty to reduced charges in both cases and was sentenced last month to seven years in prison.

The tapes, which reportedly propelled federal agents into wide-ranging inquiries including the extent of organized-crime involvement in city and state construction projects, were put under seal again by federal court order Nov. 23.

Donovan declined through a spokesman yesterday to comment on the possibility of contacts with Masselli beyond those "on the job site." Masselli, who does not have to surrender to authorities until after the holidays, could not be reached.