Applications for U.S. home mortgages edged up slightly last week as a rise in refinancing activity was offset by a lack of demand for purchases, an industry group said Wednesday.

MBA has expanded the number of participants in its survey and the firm says it will capture about 75 percent of retail and direct mortgage applications, up from 50 percent previously.

The indexes were rebenchmarked as of January to reflect the new sample.

The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity, which includes both refinancing and home purchase demand, rose 0.6 percent in the week ended Sept 16.

The MBA's seasonally adjusted index of refinancing applications gained 2.2 percent, while the gauge of loan requests for home purchases fell 4.7 percent.

Fixed 30-year mortgage rates averaged 4.29 percent, unchanged from the week before.