The federal government has levied a $786,000 fine for alleged safety violations against the Newport News Shipbuilding and Dry Dock Co., the largest safety-related penalty against a private employer ever, it was announced yesterday.

The fine, more than double the size of the previous record, followed a court-contested 60-day inspection of the Virginia shipyard during which federal safety officials said they found 617 alleged violations of U.S. occupational safety and health laws.

A team of 12 inspectors allegedly found unguarded machinery, exposed electrical parts, unguarded scaffolds and deck openings, and improper storage of flammable liquids at the site, the largest private shipyard in the nation.

Inspectors also charged that employes in the yard's work force of 23,000 were exposed to excessive levels of asbestos, chromate, silica, cadmium and other toxic substances, that the company was lax in medical surveillance and that there were numerous instances of excessive noise.

Assistant Labor Secretary Eula Bingham, who heads the federal occupational safety agency, said yesterday, "The magnitude and the nature of the alleged violations . . . reveal significant deficiencies in the shipyard's job safety, health and medical programs.

"When the company remedies these deficiencies, the thousands of workers at the shipyard can begin to realize the safe and healthful work place promised them (by federal law)."

A Newport News Shipbuilding spokesman said the company, a subsidiary of the Houston-based conglomerate Tenneco Inc., would have no comment until the allegations have been reviewed.

The spokesman also declined to estimate the cost of correcting the alleged violations. The Norfolk Naval Shipyward in nearby Portsmouth, Va., recently estimated it would cost at least $81 million to correct 195 violations cited in a three-week federal inspection in 1978.

Newport News Shipbuilding has 15 days to respond to the charges, after which the fine is subject to review by the Occupational Safety and Health Review Commission, an independent panel that can alter the fine or let it stand.

If imposed, the fine can be appealed through the federal court system and ultimately to the U.S. Supreme Court.

The penalty is the largest levied by the U.S. Occupational Safety and Health Administration on an employer since the federal agency was created nine years ago. The previous record, a $340,200 fine levied last year against the Berwick (Pa.) Forge and Fabricating Co., a railroad car manufacturer, is being appealed.

Federal officials said the total of 617 alleged violations was not a "laundry list" of every deficiency or hazard that may have existed during the inspection, which was delayed while the company twice went to federal court to contest procedures.

"We had hoped, and we so advised the company last fall, to avoid the Mickey Mouse, picky citations we unfortunately have the reputation for writing", said OSHA area director Leo Carey.

The inspection was prompted by complaints last year by the United Steelworkers Union, which represents 15,500 blue-collar workers at the shipyard.

The company first resisted an inspection of the 470-acre facility last August, claiming a warrant secured from a U.S. magistrate did not authorize a comprehensive look at working conditions.

But later in the month, in a compromise accepted by U.S. District Judge Walter Hoffman in Norfolk, the company agreed to a "wall-to-wall" inspection, disagreeing only on the length of the inquiry and how many OSHA agents would be involved.

Among the 66 health violations alleged, OSHA said the shipyard's medical staff did not notify 11 employes when their tests showed lung abnormalities, did not refer them for further tests or treatment, and in some cases did not keep required records of some injuries and illnesses.

Among the 551 safety violations alleged, OSHA said in some cases workers were not issued or failed to wear hard hats, had inadequate protective boots and were issued respirators that were inadequate or ineffective because the wearers had beards.

The steelworkers union won a hotly contested election to represent the shipyard in 1978 from the independent Peninsula Shipbuilders' Association. The union in 1979 abandoned a 13-week strike to force the company to go to the bargaining table. But last October, the company relented and agreed to recognize the steelworkers union as the legitimate bargaining agent.

Newport News Shipbuilding President Edward Campbell said last February the company has had the industry's best safety record for each of the last four years, and contented that OSHA initiated its inspection to help the steelworkers union in its struggle for recognition.

Newport News Shipbuilding is the biggest private employer in Virginia with a $430 million annual payroll.

The two biggest ships ever built in the Western Hemisphere -- both of them oil tankers -- were launched at the shipyard last year.