Specialty clothing retailer Gap Inc has reported a slight increase in November comparable store sales, helped by gains at two of its core brands.

The San Francisco-based retailer, which operates 3,100 stores, saw total comparable store sales rise 2% in November. Gap and Old Navy posted respective 2% and 3% increases, while Banana Republic posted a 1% decline.

Gap said the results were partially affected by a calendar shift, but it expects a portion of this difference to reverse in December.

Net sales reached US$1.63bn during the four weeks to 24 November, up 8% from $1.52bn in the same period of last year.

"We are pleased with how we competed and delivered in November, providing a seamless experience for our customers whether they shopped in stores, online or on their mobile devices," said company chairman and CEO Glenn Murphy.