Federal savings-and-loan regulators likely hurt taxpayers by reducing competition among private investors during the 1988 bailout of failed institutions, a study says.

The study sharply criticized the now-defunct Federal Home Loan Bank Board and the Federal Savings and Loan Insurance Corp. for their handling of S&L rescues that year."It appears on the basis of all the available facts that FSLIC and the bank board were less than successful in fulfilling their self-imposed competitive mandate," said the study by the Washington law firm of Steptoe and Johnson.

Better handling of bids likely would have meant more competition and a savings for taxpayers, it said.

The unreleased four-volume report, ordered by the S&L bailout law enacted in August 1989, has been delivered to the oversight board of the Resolution Trust Corp., headed by Treasury Secretary Nicholas F. Brady, and to the House and Senate banking committees. The Associated Press reviewed a copy.

The trust corporation replaced the FSLIC as the agency responsible for managing and disposing of failed S&Ls. The bank board was dismantled, with many of its responsibilities passed to the Office of Thrift Supervision, a new agency in the Treasury Department.

The 1988 deals, many thrown together in the last few days of the year to take advantage of an expiring tax loophole, have been sharply criticized by congressional Democrats. They will cost taxpayers an estimated $69 billion over the next decade.

The report focused in particular on deals conducted under the bank board's Southwest Plan, in which 87 failed S&Ls in Texas were combined into 15 larger institutions and transferred to new owners with government assistance.

The report said that solicitations sent in February 1988 to potential buyers of failed S&Ls lacked key information, such as the number and identity of the thrifts to be sold in each package or their size or financial condition.