Applications for refinancing on U.S. home mortgages jumped last week, even as demand for new home purchases dried up, 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, rose 4.1 percent in the week ended Dec 9.

The MBA's seasonally adjusted index of refinancing applications climbed 9.3 percent, while the gauge of loan requests for home purchases tumbled 8.2 percent.

The refinance share of total mortgage activity rose to 79.7 percent of applications from 76.0 percent the week before.

Fixed 30-year mortgage rates averaged 4.12 percent, down 6 basis points from 4.18 percent the week before. It was the lowest rate this year, MBA said.

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