Applications filed with American mortgage lenders for home purchases declined for a fifth week in six, more signs that rising borrowing costs and high prices are putting the brakes on the housing market.

The Mortgage Bankers Association’s weekly home-purchase index declined 0.4% to 399 from 400.8 in the week ended March 3. An increase in refinancing helped boost the Washington-based group’s overall index of mortgage applications by 0.7% last week.

The average rate on a 30-year fixed mortgage rose to a three-month high of 6.31%. Further increases in borrowing costs may exacerbate a recent slowdown in sales and produce more of a drag on economic growth, economists said.

“The speed with which long-term rates are now rising could intensify the housing slowdown,” an economist at Bank of Tokyo-Mitsubishi UFJ in New York, Ellen Zentner, said. “In the long-term, it means fewer sales and refinancing and slower consumer spending.”

Refinancing has been a source of cash for consumers during the past few years. While the mortgage bankers group’s index of refinancing increased by 2.6% to 1614.4 last week, it’s down 26% from a year ago.

The rise last week in refinancing helped the mortgage bankers group’s overall index increase to 575.6 last week from 571.5.

The average 30-year rate increased last week from 6.19% a week earlier and is up from 5.69% a year ago, the mortgage bankers group’s data showed.

Purchase applications have declined by a quarter since reaching a high in June of last year, reinforcing a forecast by the National Association of Realtors that home sales will fall 4.7% this year from a record in 2005.

Rising inflation concerns have pushed up Treasury yields, triggering an increase in mortgage rates. The yield on the Treasury’s 10-year note maturing February 2016 increased 15 basis points since February 24. A basis point is 0.01 percentage point.

At the current 30-year fixed rate of 6.31%, borrowing costs for every $100,000 of a mortgage would be $620 compared with $580 a year ago.

The average 15-year mortgage rate rose to 5.97% from 5.84% the week ending March 3, yesterday’s report showed. The average rate on a one-year adjustable mortgage rose to 5.69% from 5.64%.

“We see the slowdown crystal clear in the MBA purchase index, and it’s starting to show up in monthly sales data,” said Anthony Chan, chief economist at JPMorgan Chase & Co.’s private client services group in Columbus, Ohio. “The one thing that was supporting the market, low mortgage rates, is being taken away.”