Holiday season online spending got off to an early and strong start, spurred by rising consumer confidence and retailer promotions ahead of the traditional big shopping days, comScore Inc said on Wednesday.

From Nov. 1 through Nov. 18, $10.1 billion was spent online, a 16 percent increase versus the corresponding days last year, comScore reported. Nov. 8 has been the heaviest online spending day of the season so far at $829 million, it added.

"Recent 5-year highs in consumer confidence and early retailer promotions appear to be serving as wind in the sails for the beginning portion of the holiday season, with consumers opening up their wallets early and often," comScore Chairman Gian Fulgoni said in a statement.

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E-commerce accounts for 5 percent to 10 percent of total consumer spending in the United States. However, it is growing much faster than bricks-and-mortar retail as shoppers are lured by low prices, convenience, faster shipping and wide selection.

ComScore expects online retail spending to rise 17 percent to $43.4 billion this holiday season. That is above the 15 percent increase last season and ahead of the retail industry's expectation for a 4.1 percent increase in overall spending this holiday.