Retail sales nationally are down on forecasts, and most retailers are doing worse than this time last year.

Peak retail industry body the Australian Retailers Association's (ARA) week-by-week tracking of retail trade during the Christmas period has found that last week over 65 percent of retailers were trading in levels below that of the correponding period last year.

Retailers comparing trading from December 12 to 18, 2010 to the same time last year said just 24 per cent were trading above and over 10 percent were trading the same as last year.

ARA executive director Russell Zimmerman said retailers were banking on a boost in sales during the final days leading into Christmas.

"These final days will be critical if retailers are to meet projections of $39.9 billion in national retail sales for the Christmas trading period.

"Traditionally consumers do leave their shopping until the last minute so retailers have all their fingers and toes crossed that shoppers will be rushing to the tills and taking advantage of extended trading hours.

"By all accounts this hasn't been a very joyous Christmas for retailers who are slashing prices pre-Christmas just to get consumers in the door," Zimmerman said.