Congress yesterday heard "chilling" new figures on the spiraling cost of the first phase of the government's efforts to solve the savings and loan problem, including assessments that it would have been cheaper to close three ailing thrifts than to pay billions to some of the nation's wealthiest investors to kept them going.

House Banking Committee investigators estimated that the 96 thrift cleanup agreements reached during 1988 would cost the Treasury $71 billion over 10 years, including tax breaks, prompting renewed calls for changes to the agreements.

"These so-called deals bear all the earmarks of a giveaway, with the recipient of the government largess being some of the fattest of the nation's financial fat cats," said committee Chairman Henry Gonzalez (D-Tex.). The details about the incentives presented a "chilling" picture of the now controversial deals, he said.

Federal Deposit Insurance Corp. Chairman L. William Seidman agreed with committee members that the deals are a "disaster" and that the government is going to have to "pay through the nose" as a result. He said the government could exercise cost-saving options built into the agreements, but it would require a great deal of money at the outset.

"Many billions" could be saved, Seidman said, but "many more billions will be needed" to do it. "We would have to put $4 in upfront cash for $1 in savings," he said.

Committee staff accountant William Sanchez, who spent several months evaluating the agreements, reported that the government would have been better off if it had not made deals with three very wealthy investors: Robert M. Bass, who led a group that acquired American Savings in California, a deal it is now estimated will cost taxpayers $5.2 billion; Carolyn Hunt, daughter of Texas oilman H.L. Hunt; and Ronald O. Perelman, owner of the Revlon cosmetics empire.

Sanchez told the committee that "information available to the {Federal Home Loan} Bank Board, at the time the deals were consummated, indicated that the three deals would cost about $4.8 billion more on a cash basis than had the institutions been liquidated. Further, since the original estimates were developed, the cost of assistance on the three deals has increased by 25 percent, to $20.8 billion."

The now defunct bank board made many of the 96 agreements in the last days of 1988, rushing to complete them in time to allow purchasers of failed thrifts to take advantage of tax breaks that expired at the end of 1988.

The board, which was low on cash and loathe to ask for more from Congress, came up with other incentives to investors to take over 223 failing thrifts. In addition to billions in tax breaks, the board granted acquirers an estimated $20 billion in notes, on which the government must make interest payments, and yearly subsidies to offset losses from bad loans and other nonperforming assets.

Members of the board, including former chairman M. Danny Wall, defended their efforts to a largely skeptical committee yesterday. One former member, Lawrence J. White, said that in retrospect he does not think the board should have excluded bidders other than the Bass group in negotiating the Bass sale.

Two former bank board officials, Thomas J. Lykos and Roger F. Martin, said they are working for firms that do business with American Savings.

The original cost of the agreements was estimated at $40 billion. That figure has been moving up steadily, and the FDIC, the Government Accounting Office and the House Banking Committee staff all are in general agreement that the figure is now about $67 billion in direct assistance, plus about $4.5 billion in tax assistance.

The number could go significantly higher, according to the GAO and the committee staff, because it is tied to interest rates and the real estate markets. In addition, future interest costs are being computed by the FDIC, and those figures could add billions to the total in future years.

"Go over these contracts with a fine-tooth comb," Rep. Charles E. Schumer (D-N.Y.) urged Seidman, who is now charged with managing the agreements. The Resolution Trust Corp., which Seidman also heads, is slated to release an examination of each of the deals next week with recommendations on whether savings can be had by prepaying notes or buying back real estate and other assets from the thrifts in order to end subsidy payments the government is making.

"The real question is whether they should have tried to undertake the transactions at all, given they had no cash and doubtful credit," Seidman said. "They might have gone to the Congress and said, look, this is a disaster. Give us some more money to handle it."

Sanchez said the committee staff found that a third of the 96 investors who acquired the thrifts -- with billions in government assistance -- put up no money of their own. He said that two institutions, James M. Fail's controversial Bluebonnet Savings and Sunbelt Savings, both of Texas, "acquired assets of $6.7 billion and are projected to receive $13.5 billion in assistance -- or more than $2 in assistance for every dollar of assets acquired."

Sanchez said an unusual decision to permit a regulatory exception allowed Hunt to walk away from hundreds of millions of dollars in obligations at Southwest Savings in Texas, costs that must now be borne by taxpayers.