An accounting firm officer with close ties to Reagan administration officials received inside information on the preliminary bids of rivals before his company and an associated firm submitted their winning bid for a major 1982 Social Security contract, the General Accounting Office said yesterday.

The 1982 contract involved a systems modernization program for the Social Security computer system, eventually awarded to Electronic Data Systems (EDS) for an initial $6.3 million, which subsequently grew to $33 million over five years. Deloitte, Haskins and Sells, the accounting firm, was the major subcontractor, receiving about 30 percent of the contract.

Rep. Jack Brooks (D-Tex.) said he convened yesterday's hearing by his House Government Operations subcommittee to determine whether "efforts by the Social Security Administration to modernize its computer operations have been undermined by political favoritism, contract rigging and official corruption."

Brooks said an earlier investigation had revealed that while preparing the bid, Deloitte, Haskins and Sells had been allowed to set up an office in the suite of then-Social Security commissioner John A. Svahn, had access to key officials, and had taken Social Security officials to lunches and dinners frequently.

The accounting firm officer, partner James S. Dwight, served in the California gubernatorial administration of Ronald Reagan with Svahn. Later, as head of the Social and Rehabilitation Service (SRS) of the Department of Health, Education and Welfare during the 1970s, Dwight hired Svahn as a top SRS official. He also participated in the hiring Svahn at the firm.

A statement issued yesterday by the accounting firm denied breaking any laws or regulations or taking actions that "in any way improperly affected the outcome of the procurement process."

Dwight said in his testimony yesterday that before EDS submitted its final bid, he met with Marshall Mandell, a top Social Security official who years earlier had been hired by SRS when Dwight headed it, and discussed the general level of the preliminary bids of other firms. But he insisted that he had not passed any of the information on to EDS, and that EDS' decision to lower its final bid had not been influenced by the information.

GAO official Milton J. Socolar said that an investigation requested by Brooks had produced testimony from Mandell, who earlier had refused to cooperate, that, late in 1982, after initial bids were received, Dwight came to see Mandell and had said he "had heard that EDS/DHS {Deloitte, Haskins and Sells} was the high bidder and wanted to know the details."

Socolar said Mandell had testified to the GAO that he told Dwight "the details of each bid and the amounts," and that while the EDS/DHS bid was technically superior, "its cost proposal was too high and it would have to come down by $1.5 to $2.5 million" from its initial $8.7 million level to about $7 million, to win.

At yesterday's hearing, Mandell generally confirmed Socolar's account of his testimony to the GAO. But Dwight insisted that when he came to see Mandell, it was not to obtain information on other firms in order to alter a bid, but to tell him that EDS/DHS had already decided to lower its bid.Information about other firms' preliminary bids was an "outgrowth of the conversation," Dwight said. He said he had not passed the information on to others.

EDS official David L. Jenkinson testified, however, that when EDS decided independently to lower the bid to about $6 million to ensure competitiveness, Deloitte, Haskins and Sells employes responded that they had "information from inside the Social Security Administration" that it need not be dropped below $7 million to win. Two officials of the firm denied it.