WASHINGTON - The average U.S. rate on the 15-year fixed mortgage fell last week to its lowest level on record, making refinancing and home-buying more attractive to those who can qualify.

Mortgage buyer Freddie Mac said Thursday that the average rate for the 15-year fixed loan fell to 2.61 percent. That's down from 2.64 percent last week and the lowest rate on records dating back to 1991. The previous record low of 2.63 percent was reached in November.

The average rate on the 30-year fixed mortgage also moved closer to its record low, dropping to 3.40 percent. That's down from 3.41 percent last week and just above the previous record of 3.31 percent, also reached in November.

Low mortgage rates are helping drive a housing recovery that began last year. Home prices are rising. Sales of new and previously occupied homes are up this year. Builders broke ground on homes in March at the fastest annual pace in nearly five years.

Sales of new homes rebounded last month to a seasonally adjusted annual rate of 417,000, the government reported Tuesday. The increase added to evidence of a sustained housing recovery at the start of the spring buying season.

New-home sales are still below the 700,000 pace considered healthy by most economists. But the pace has increased 18.5 percent from a year ago. Most economists see more gains ahead, as housing is likely to remain a consistent driver of economic growth this year.

Mortgage rates are low because they tend to track the yield on the 10-year Treasury note, which has fallen in recent weeks.

The Federal Reserve has been buying Treasury bonds since the fall.

That has helped to lower the yield. And in recent weeks, concerns that the U.S. and global economies are slowing have led investors to shift money into safer assets, like Treasurys, and away from stocks. Greater demand for Treasurys raises their price and lowers their yield.

The yield was 1.72 percent at midday Thursday, up from 1.69 percent last week but still at a historically low level.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country on Monday through Wednesday each week. The average doesn't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for 30-year mortgages rose to 0.8 point from 0.7 point last week. The fee for 15-year loans was unchanged at 0.7 point.

The average rate on a one-year adjustable-rate mortgage fell to 2.58 percent from 2.63 percent last week. The fee for one-year adjustable-rate loans increased to 0.5 point from 0.4.

The average rate on a five-year adjustable-rate mortgage rose to 2.62 percent from 2.60 percent. The fee declined to 0.3 point from 0.5.