The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity for the week ended April 14 decreased 1.7 percent to 569.6 from the previous week's 579.4.

Borrowing costs on 30-year fixed-rate mortgages, excluding fees, averaged 6.56 percent, up 0.06 percentage point from the previous week, its highest level since the week ended June 7, 2002 when it reached 6.65 percent.

Historically low mortgage rates have fueled a five-year housing boom, helping support the U.S. economy's recovery from recession despite uncertain business investment.