NEW YORK, Reuters - Applications for U.S. home mortgages fell last week and interest rates declined to their lowest level since May 2013, an industry group said on Wednesday.

The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity, which includes both refinancing and home purchase demand, fell 3.3 percent in the week ended Dec. 12.

The MBA's seasonally adjusted index of refinancing applications was unchanged, while the gauge of loan requests for home purchases, a leading indicator of home sales, fell 6.9 percent.

Fixed 30-year mortgage rates averaged 4.06 percent in the week, the lowest since May 2013. They were down 5 basis points from 4.11 percent the week before.

The survey covers over 75 percent of U.S. retail residential mortgage applications, according to MBA.

(Reporting by Caroline Valetkevitch; Editing by Leslie Adler)