Web holiday sales are up 24 percent over a year ago, in line with estimates. However it is believed the shopping season may extend longer online this season as consumers appear to be confident that expedient shipping would get their gifts in time, comScore said Thursday.

Spending online from November 1 through December 12 has reached $17.56 billion, up from $14.13 billion last year. In fact, comScore said December 11 set a new record for online spending, with consumers spending $661 million online.

The research firm noted that growth rates were slightly below expectations for the beginning of this week, but said that a shift to more spending in the latter part of the week as well as into next week thanks to promises of pre-Christmas deliveries later into the season than last year is quite possible.

Such a belief may be backed up by online retailers' better shipping policies. A recent survey showed the number of firms promising pre-Christmas delivery for orders placed using standard shipping by December 18 or 19 rose to 39 percent, up from 19 percent last year.

"Because shipping was so reliable last year, it's conceivable that more consumers are opting to procrastinate this year," comScore Networks chairman Gian Fulgoni said.

If the past three years were any indication, this week will be the peak in holliday sales. In 2004 and 2005, sales were roughly the same going into next week before dropping off dramatically during the week of Christmas. However, with shipping becoming more reliable, that trend could be broken in 2006.

Overall, online spending is up 24 percent for non-travel in both the non-holiday and holiday periods. Spending during January through October reached $77.5 billion, up from $62.6 billion in the previous year. comScore forecasts holiday sales to reach $24.3 billion this year, up from $19.6 billion in 2005.