A top officer of Burton, Parsons & Co. Inc. of Seat Pleasant, Md., yesterday denied allegations that he sought to influence two Food and Drug Administration employes with frequent entertainment.

At a hearing before the House subcommittee on oversight and investigations, John A. "Tommy" Manfuso Jr. said: "Neither my brother nor I ever sought any action from FDA on any basis other than the merits of our products."

The hearing was to look into charges that Burton, Parsons gained a virtual monopoly over a segment of the FDA-regulated soft contact lens industry between 1974 and 1978 while it repeatedly entertained two top FDA regulators.

The two FDA employes, microbiologist Mary Bruch and ophthalmologist Dr. Arnauld Scafidi, are scheduled to testify when the two-day hearing resumes on Tuesday. Both are also subjects of an FBI investigation and of an internal FDA probe.

Tommy Manfuso and his brother Robert, who ran the privately owned family business, sold it in 1979 to a U.S. subsidiary of Nestle S.A. of Switzerland, reportedly for $110 million. According to industry sources, the company's rapid growth was a direct result of FDA decisions.

Six large boards prepared by the subcommittee from subpoenaed company expense accounts showed a four-year pattern of lunches, dinners and gifts paid for by the company for the two FDA officials. Throughout the same four years, the FDA was making decisions important to Burton, Parsons, all of which were directed by Bruch, whose powers at FDA reportedly far exceeded her title.

The boards also showed numerous occasions when Bruch joined Tommy Manfuso and other company employes at race tracks such as Pimlico, Bowie, and Laurel.

In answer to questioning by House members, Keith Whitham, a former company employe, denied that he or Manfuso often placed bets for Bruch in a way that assured she would be a winner.

The subcommittee then introduced a surprise witness, John E. Bryer, a former Burton, Parsons employe who once shared a house in Bowie with Whitham.

Bryer said that Whitham told him that Manfuso or he would bet for Bruch on every horse in a race. "Mary always won," Bryer claimed Whitham had told him.

"He [Whitham] indicated it was kind of a sham, and it would be better just to hand her the money," Bryer told the subcommittee.

Asked by subcommittee counsel Susan Leal, "Is Mr. Bryer a liar?" Whitham said of his former housemate, now sitting next to him at the witness table, "Yes."

In his testimony, Manfuso called the allegations "absolutely ludicrous," adding: "I never bet on a race horse with my money for Mrs. Bruch."

The key question at the hearing was whether Burton, Parsons executives caused Bruch to make decisions that aided the company.

In 1978, the FDA followed Bruch's urging and banned the sale of inexpensive salt tablets used by soft lens wearers to mix a homemade purifying solution. As a result, lens wearers were forced to turn to a costlier preserved saline solution. Burton, Parsons virtually controlled the whole market on the saline solution because of FDA actions. (The FDA lifted its ban on the salt tablets in mid-1980 after complaints from soft lens wearers.)

The ban of salt tablets was justified in a study prepared by Scafidi. The committee alleges that the study was based on fraudulent research data.

All witnesses yesterday denied they were trying to influence the FDA employes. But each witness also allowed, in retrospect, that perhaps the entertaining was excessive.

But committee members were not satisfied.

"This total record literally screams of impropriety," said Douglas Walgren (D-Pa.), whose opinion seemed to reflect that of all the members at the hearing.