The volume of U.S. mortgage applications fell to a seven-week low even as most home borrowing costs declined last week, the Mortgage Bankers Association said on Wednesday.

The Washington-based industry group said its seasonally adjusted index on mortgage applications fell 1.9 percent to 380.6 in the week ended April 6. This was the lowest level since 372.9 in week of Feb. 16. 

The refinance share of mortgage activity decreased to its lowest level since September 2008, 38.4 percent of total applications, from 38.5 percent the previous week. The adjustable-rate mortgage (ARM) share of activity decreased to 6.3 percent of total applications.

The average contract interest rate for 30-year fixed-rate mortgages with conforming loan balances ($453,100 or less) decreased to 4.66 percent from 4.69 percent. The average contract interest rate for 15-year fixed-rate mortgages decreased to 4.08 percent from 4.09 percent.