At least nine former officials at the Department of Health and Human Services went to work for a giant Florida health plan from 1981 to 1986 -- a period when the government was making key decisions about the fate of the federal contractor, General Accounting Office investigators reported yesterday.

The extent of the "revolving door" between the government and International Medical Centers was disclosed during a congressional hearing into the causes of IMC's collapse earlier this fall amid allegations of fraud, mismanagement and influence-peddling.

"These officials accepted salaries and consultants' fees well above the norm and, in return, helped IMC charge the federal government for millions of dollars in improper payments that are not likely to be recovered," said Rep. Ted Weiss (D-N.Y.), who called the hearing.

Weiss was referring to testimony yesterday by HHS Inspector General Richard P. Kusserow that IMC owes Medicare nearly $12 million in overpayments. Kusserow said he was pessimistic the bankrupt health plan could pay back the money.

Until last May, IMC was the largest contractor under a special program to allow Medicare recipients to enroll in health maintenance organizations and other prepaid health plans. With more than 130,000 enrollees throughout southern Florida, IMC received nearly $1 billion in payments until it was kicked out of the Medicare program for violating U.S. regulations.

The collapse of IMC embarrassed the Reagan administration, which has sought to promote the use of HMOs by Medicare, the federal insurance program for the elderly.

IMC also has come under criticism for tactics including its effort to curry favor through campaign contributions and the hiring of former officials or people with government connections. Legislators have charged that IMC's lobbying efforts detracted from efforts to fix extensive operating problems.

David Williams, director of the GAO's office of special investigations, said that in 1986 IMC paid $300,000 to the consulting firm of former White House aide Lynn Nofziger; nearly $800,000 to a Washington law firm that had hired two former top HHS lawyers; more than $60,000 to the Republican-connected lobbying firm of Black, Manafort & Stone, and more than $54,000 to the law firm of John Sears, former campaign manager for Ronald Reagan.

Williams also identified nine former HHS officials who went to work for IMC, often at substantially more than their government salaries. Juan A. del Real, former HHS general counsel, went to work at an annual base salary of $325,000, while Wayne Fowler, who had been responsible for HMO operations at HHS, started at $165,000.

Kusserow said an HHS official who dealt with IMC, Theodore Saffran, accepted loans from IMC to take gambling junkets and "only partially repaid them." He said the Justice Department found "insufficient evidence" to support an indictment and that the matter has been referred to the Health Care Finance Administration. Saffran declined to comment yesterday.

During the hearing, C. McClain Haddow, former HHS chief of staff, illustrated the lobbying campaign when he testified that he had received calls on IMC from Nofziger and Jeb Bush, the vice president's son and then a Republican Party official in Dade County, Fla.

Haddow, who is scheduled to begin a prison term next month for violating conflict-of-interest rules on another matter, told reporters that former HHS secretary Margaret M. Heckler referred Jeb Bush to him because she saw "her political future as being tied very closely to {George} Bush."

Jeb Bush did not return a telephone call yesterday.

Kevin Moley, an HHS official in charge of HMO policy and former campaign aide to George Bush, said in an interview that Jeb Bush talked to him at the time, and said he was calling on IMC's behalf simply because IMC's chief executive was a prominent businessman and big Republican contributor in Florida.