NEW YORK (AP) _ Supreme Court nominee Robert H. Bork's avowed opposition to antitrust laws has raised concern among some critics that if confirmed he would grant extensive leeway to businesses at the expense of consumers.

Bork's antitrust writings, his academic specialty as a Yale Law School professor, sharply contrast with the judicial restraint and respect for legislative decisions he has advocated elsewhere.

In a 1978 book written by Bork titled ''The Antitrust Paradox: A Policy at War with Itself,'' he argues that most antitrust laws passed by Congress and Supreme Court decisions on antitrust issues are incorrect, counterproductive and economically inefficient.

''There's no question in my mind that even among conservative critics of antitrust law, he's an extra-conservative person,'' said Robert Pitofsky, an antitrust authority and former federal trade commissioner, now dean of Georgetown University Law Center.

''If Bork had his say on the Supreme Court, we would have a radically different enforcement of antitrust laws.''

Aryeh S. Friedman, assistant professor of legal studies at the Wharton School who uses Bork's book in his classes, said it shows an ''activist conservative approach to antitrust laws.''

Because Bork contends that efficiency is the original and overriding goal, Friedman said, ''the practical consequences may be a relaxation of antitrust enforcement.''

The 60-year-old appellate judge's stand in business-related matters has become one of the focal points in his Senate confirmation hearings, which started this past week. President Reagan's nomination of Bork has provoked an emotional fight between his conservative backers and liberal critics.

Sen. Howard Metzenbaum, D-Ohio, a supporter of antitrust legislation and business regulation, told Bork he found the judge's views ''troubling.''

But Bork said his antitrust arguments respect consumer interests. He also said some antitrust regulations have the unintended effect of suppressing competition and that corporate mergers don't necessarily lead to monopolies.

''I don't think two or three companies can control a market unless they conspire,'' Bork said.

Beginning with the Sherman Act in 1890, antitrust laws have played a significant role in the economy by preventing monopolies and other collusive practices, such as price-fixing and market-sharing agreements, that suppress competition and hurt consumers.

In his book, Bork argues that some types of price fixing, such as manufacturers attempting to set retail prices, aren't anticompetitive but usually are meant to encourage retailers to compete by offering services with their products.

Metzenbaum argued that it is questionable whether consumers receive such services. Instead, he said, consumers lose the opportunity to buy from discounters.

Bork's critics, which include the American Civil Liberties Union, New York Bar Association and AFL-CIO, fear he might tip the balance on the high court to reject longstanding legal protections in other business-related areas besides antitrust, including work place safety and sexual harassment of employees.

The critics contend that as a federal judge, Bork frequently has sided with companies, in one case ruling an employer was justified in ordering female factory employees to be sterilized or face dismissal.

In another matter, Bork upheld a company's right to fire workers distributing union signup cards. He also strongly dissented from a significant ruling that a victim of sexual harassment by her supervisor was entitled to sue her employer for sex discrimination.

Public Citizen Litigation Group, a Ralph Nader organization based in Washington, said in a study of Bork that in split cases in which the government was a party, he ''voted against consumers, environmental groups and workers almost 100 percent of the time and for business in every such case.''

Bork has rejected what he calls the unfair characterizations of his record by Public Citizen and other groups. But his critics contend that Bork has changed his views for the purpose of winning Senate confirmation.

''If you look at my decisions on race, on women, on labor unions, on individuals versus the government, you will find no consistency along those lines,'' Bork said during the hearings. ''You will find no political axis, no political line along which those decisions line up. They go both ways.''

No official position on Bork has been taken by the National Association of Manufacturers or U.S. Chamber of Commerce, two of the most important business lobbying concerns in Washington. Spokesmen for both groups said it was standard policy not to comment on executive appointees.

But to Bork's critics, big-business support for him was obvious from an unusually public accolade published in the Wall Street Journal last month. It was written by Roger B. Smith, chairman of General Motors, the largest U.S. industrial company and a longtime opponent of business regulation.

''From what I know about him and from what I have read about his view of judicial life, I believe Judge Bork has an enduring commitment to the rule of law,'' Smith wrote. ''I think Judge Bork should be confirmed as a justice of the Supreme Court and have the opportunity to continue in the tradition of judicial restraint.''

Although GM spokesman Donald Postma said Smith was only expressing a personal opinion, the column received considerable criticism, even within the auto industry.

Automotive News, a major trade publication, said that in writing such a column for a national business daily, ''Smith clearly stepped beyond speaking as an individual citizen.''

End Adv Sept. 19-20