Albert Nipon, chairman of a women's clothing design firm whose dresses have been worn by Nancy Reagan and Rosalynn Carter, was indicted yesterday by a federal grand jury in Philadelphia on charges that he bribed two Internal Revenue Service agents to avoid paying nearly $800,000 in 1978 personal and corporate income taxes. The agents were also indicted.

U.S. Attorney Edward Dennis Jr. said yesterday that Nipon, 57, paid $200,000 in bribes to IRS agents in what he called "one of the largest bribery schemes ever uncovered" to defraud the government.

The indictments said that an additional $15,000 was passed along to an IRS supervisor in exchange for a favorable reading of Nipon's 1980 tax returns.

Nipon was also charged with two counts of income tax evasion. In a statement yesterday, he said that the taxes in question resulted mainly from disputed tax write-offs.

"I have had no previous problems with the Internal Revenue Service," the statement said. "I fully recognize the seriousness of these charges."

The Nipon fashion line, begun in 1972, is credited with reviving the dress industry after sportswear and separates had cut into sales.

The indictments allege that the two agents accepted the bribes in exchange for making changes in Nipon's 1978 and 1979 income tax returns. Dennis said that criminal charges against Nipon are based only on the 1978 return.

Nipon, who lives in Gladwynne, Pa., is said to have claimed taxable income in 1978 of $32,282 and to have paid a tax of $19,834. The indictment alleges Nipon's personal taxable income was $884,308 and that he owed $508,063 in taxes.

That year, Albert Nipon Inc. claimed taxable income of $1,874,536 and paid $744,297 in taxes. The indictment says the company's income was really $2,407,468 and that taxes should have been $1,051,550.

In his statement, Nipon also said he "will be depositing the sum of $1 million with the Internal Revenue Service to provide a fund to satisfy any additional tax liability . . .

The alleged discrepancy in taxes is primarily attributable to the disallowance of expenditures for improvements, furnishings and renovations to my home which were paid for by the company," the statement continued.

"Both the amount of the payment and whether they could be made by the company are controversial questions in this lawsuit. My attorneys believe that certain of these expenses are legitimate business expenditures . . ."

Dennis said the indictments were part of a continuing investigation into illegal activities of IRS agents. Seven other people have been indicted in the last year on unrelated matters.

IRS agent Meyer Weiss, in the Philadelphia office, and retired agent Edmond Costantini, of Broomall, Pa., were charged with conspiracy to defraud the government and accepting bribes "to commit . . . a fraud on the United States in violation of their official duty," according to the indictments. Neither Weiss nor Costantini could be reached for comment yesterday.

The indictments allege Nipon gave the bribes in four installments and that Costantini paid IRS supervisor Irving Suval $15,000 in 1982 so that Suval would manage the examination of the 1980 returns of Albert Nipon Inc. "in order to ensure a result favorable to the taxpayer."

Suval, who is no longer employed by the IRS, was not named in yesterday's indictments.

Albert Nipon Inc.'s sales for this year are expected to reach almost $60 million. The line includes shoes and perfume as well as casual, business and evening dresses. The tailored but feminine dresses, which are considered middle to upper-middle scale in cost, are priced from $100 to $2,000 and have been bought by such clients as Dina Merrill, Mary Tyler Moore and Barbara Walters as well as the first ladies. Last year, the Nipons were guests at a White House state dinner.

Nipon's wife, Pearl Nipon, is in charge of the design department of the Philadelphia-based firm. Although she signed the joint personal tax forms, she was not named in yesterday's indictment.

Albert Nipon was "at work today, and so is Pearl," Nipon spokeswoman Ellen Karasik said. "His son Larry is president of Albert Nipon, and he's at work too. This is . . . a personal matter, and has nothing to do with the business."

American store executives in Paris yesterday for the showings of spring fashions appeared shocked by the news of the indictment.

"You've got to be kidding," Fred McCann, vice president of Sakowitz Inc., a Houston-based specialty store chain. "I've known Albert for years. He has really helped to make the business for that price range ."

Aniko Gaal, fashion director for Garfinckel's, said, "He makes wonderful, commercial clothes. They sell very well. He fills a void in the American market."