Applications for U.S. home mortgages rose last week, fueled by demand for refinancings as mortgage rates hit fresh record lows, 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, increased 3.8 percent in the week ended May 18.

The MBA's seasonally adjusted index of refinancing applications gained 5.6 percent, but the gauge of loan requests for home purchases fell for the second week in a row and was down 3.0 percent.

Mortgage rates fell as further uncertainty around the sovereign debt crisis in the euro zone pushed U.S. Treasuries yields lower, Michael Fratantoni, MBA's vice president of research and economics, said in a statement.

"Mortgage rates again dipped to new record lows in the survey, which spurred more borrowers back into the refinance market," said Fratantoni.

The refinance share of total mortgage activity climbed to 76.6 percent of applications from 74.9 percent the week before.

Fixed 30-year mortgage rates averaged 3.93 percent, down 3 basis points from 3.96 percent.

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