Applications for U.S. home mortgages slumped last week as bankers recorded the slowest refinancing activity in more than a year, an industry group said on Wednesday.

The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity dropped 12.9 percent in the week ended January 21.

The MBA's seasonally adjusted index of refinancing applications slid 15.3 percent to the lowest level since early January 2010, the group said. The refinancing index has declined sharply since October as rising interest rates and tight underwriting criteria further limited opportunities for homeowners.

The MBA's gauge of loan requests for home purchases fell 8.7 percent in the latest week.

Fixed 30-year mortgage rates averaged 4.80 percent in the week, up 3 basis points from the prior week, the MBA said.