Latest figures in the US show that total e-commerce spending during the build up to Christmas so far has reached more than US$22bn in the country, an increase of 18%, but that the rate of year-on-year growth slowed during the period.

Last Monday (10 December), online spending on all goods reached $881m in a single day, up 33% versus last year and the heaviest online spending day on record, according to digital researcher Comscore.

However, it was noted that the 18% growth rate stands well below the 26% rate at the same time last year, with analysis of online spending by household income showing that slower growth among lower income households is weighing on the overall season-to-date growth.

Comscore said that while households earning at least $100,000 have increased their online spending 28% versus last year, households making less than $50,000 have increased their spending by just 10%.

Comscore chairman Gian Fulgoni said: "The current economic realities appear to be having a negative impact on the growth in consumer spending.

"From the sub-prime housing meltdown to a decline in home values to higher gas prices and an uncertain stock market, many consumers across all income segments are either feeling the pinch this holiday season or are lacking the confidence to spend at the rate they had in the past.

"Consumers in lower income segments appear to be the most affected, as evidenced by the sluggish growth in their rate of online spending."

The research group measured total online US spending over the first 44 days of the November-December 2007 holiday season (1 November to 14 December).