U.S. federal banking regulators have set final rules on subprime mortgages, turning aside banking industry efforts to weaken them, The New York Times reported Saturday.

The rules are likely to make it harder for some borrowers to qualify for loans, although many lenders have been tightening their standards in response to rising levels of foreclosures and mortgage delinquencies, said the report.

The regulations said the most important change is that financial institutions are told that adjustable-rate mortgages should be given only to borrowers who would qualify to meet the loan terms even after the rate resets higher.

That could mean that many borrowers would qualify for loan amounts far smaller than they previously have, making it harder to buy homes and perhaps harder to refinance, the report said.

In addition, the new rules seek to slow the expansion of so-called liar's loans, which require little or no documentation of income, said the report.

Such loans have expanded in recent years, with many banks arguing that the higher rates they get on the loans more than offset the risks of default.

The Federal Reserve, the Comptroller of the Currency and other regulators expressed growing concern over the expansion of adjustable rate mortgages for subprime borrowers, because the borrowers may not understand the risks they are taking, and because some "may not have sufficient financial capacity to service a higher debt load, especially if they were qualified based on a low introductory payment," according to the report.