Amazon, the world’s largest online retailer, underlined the uncertainty facing retail sales this Christmas, forecasting fourth-quarter sales in the broad range of $6bn to $7bn – representing growth of as low as 6 per cent or as high as 23 per cent on the same period last year.

Tom Szkutak, chief financial officer, said the forecast reflected “appropriately conservative assumptions” and followed slower sales at the end of the quarter in September as consumers reacted to the turmoil on world financial markets.