US online retail sales have exceeded expectations over the Thanksgiving holiday period, which marks the start of the US festive shopping period.

Walmart.com reported that sales on the Friday after the Thanksgiving holiday exceeded expectations of 40 to 60 per cent annual growth.

Comparison shopping site Pricegrabber said sales through its site were at or greater than expectations.

The positive sales momentum will be greeted with relief by US retailers, which fear the housing slump and ensuing credit crisis will dampen sales this year.

Yesterday, retailers launched special online promotions and offers on the day dubbed Cyber Monday. It marks the season’s first spike in online sales as people return to work after the holiday weekend.

Online sales tracker ComScore forecast that sales on Cyber Monday will have exceeded US$700 million (£338.5 million) this year, up from US$608 million (£294 million) in 2006. The busiest online sales day in the US falls about 10 days before Christmas, with last year’s peak of US$666 million (£322 million) recorded on December 13.

This year, retailers including Macy’s, Sears, KB Toys and Home Depot launched special one-day offers online while others have ramped up free shipping offers.