Despite a weak economy, holiday retail online spending in the US has so far been 14% higher than the same early holiday period last year, ComScore reported on November 23, fuelled by early online deals on tablets and smartphones.

For the first 20 days of November, consumers spent $9.7 billion (£6.28 billion) online, 14% more than last year, ComScore said. Wednesday, November 16, was the heaviest onlne sales day, with $688 million (£445 million) spent.

The heightned activity has been spurred by early-season online deals, ComScore said.

Other surveys predict a surge of online sales from mobile devices like smartphones and tablets. A recent Wakefield Research survey of 400 American adults found that 70% of mobile users are making more purchases from smartphones and tablets this year than in 2010.

ComScore uses statistical modeling and its monitoring of e-commerce spending to reach its findings on retail online sales. It said the 2011 holiday season from November through to December should be up by 15% over 2010.

"With a persistent backdrop of macroeconomic uncertainty and continued high unemployment, consumers appear to be increasingly favouring the online benefits of convenience and lower prices," said ComScore Chairman Gian Fulgoni in a statement.

ComScore did a survey of 1,000 consumers that found 33% more consumers are responding to online promotions than did in 2010.

ComScore also found that 76% of consumers said free shipping is a key when deciding whether to buy online - 47% said they would abandon a purchase if they got to the online checkout and found that shipping wasn't included.

ComScore said almost half of all online purchases included free shipping in the fourth quarter of 2010.

Fulgoni said that the growth in online spending reflects a significant shift away from in-store spending. Overall, ComScore predicts some $37.6 billion (£24 billion) will be spent online in November and December, up from $32.6 billion for those two months in 2010.

ComScore said online spending from January to October totalled some $124.3 billion, up 13% from the same period last year.