NEW YORK (CNN/Money) - Rates for long-term mortgages fell to new lows this week as downward revisions of gross domestic product suggested weak growth in the economy.

Freddie Mac reported Thursday that the 30-year mortgage averaged 6.31 percent in the week ending Aug. 9, with an average of 0.6 of a point payable up front to the lender. The rate dipped from an average 6.43 percent last week and remained lower than its average 7 percent a year ago. The new average 30-year rate breaks the 32-year low recorded two weeks ago.

The 15-year fixed-rate mortgage averaged 5.69 percent, down from 5.84 percent last week and down from 6.54 percent a year ago. The 15-year averaged 0.6 of a point payable up front. This rate is the lowest recorded since the company began tracking the 15-year rate about 15 years ago, according to Freddie Mac.

One-year adjustable-rate mortgages indexed to the Treasury averaged 4.37 percent, with an average 0.6 of a point due up front, down from 4.45 percent last week and down from an average of 5.70 percent a year ago.

"Recent downward revisions of GDP for 2001 and first quarter 2002 suggest that the economy faces weak growth," Freddie Mac chief economist Frank Nothaft said. "This led to anticipation that the Fed will reduce overnight interest rates by the end of the year, if not sooner. That expectation, in turn, has created a boon for potential and existing homeowners in the form of lower mortgage rates." (Read more about increasing the resale value of a home.)

Freddie Mac (FRE: up $0.97 to $60.61, Research, Estimates), or Federal Home Loan Mortgage Corp., is a publicly traded company the government established in 1970 to provide a flow of funds to mortgage lenders. It buys mortgages from banks, bundles them and then resells them as mortgage-backed securities.

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Its products, and the products of other similar entities, have become increasingly popular as an alternative to government-backed bonds, particularly with international investors.