The volume of sales at Internet retailers held steady Friday compared to last year, despite the worsening economic outlook and signs U.S. consumers are cutting back on spending.

Online sales on Nov. 28, the day after last week's U.S Thanksgiving holiday, also known as Black Friday, were US$534 million, up 1 percent from last year, according to comScore, which tracks Internet sales. Sales on Thanksgiving, Nov. 27, were even stronger, up 6 percent to $288 million, it said.

On the surface, these numbers seem to indicate consumer spending may be more resilient than many observers forecast. But total online spending since the start of the holiday shopping season on Nov. 1 is down by 4 percent to US$10.4 billion -- a shortfall of $429 million compared to last year, ComScore said.

The company said consumers were likely persuaded to spend by steep discounts offered on Friday by Internet retailers.

Observers are now watching to see what happens today. The first Monday after Thanksgiving, sometimes called Cyber Monday, is a more important bellwether of online holiday sales that Thanksgiving or Black Friday. This is the first U.S. work day after the holiday, and roughly half of all online purchases made in the U.S. are made during work hours, ComScore said.

In previous years, the increase in online sales on Cyber Monday has been within a "few percentage points" of the overall growth rate for holiday spending, it said.

"Cyber Monday may well prove to be an important indicator of whether the decline in spending that we've seen during the first few weeks of the online holiday season will continue for the balance of the year," the market research company said in a statement.

ComScore forecast that holiday spending will be flat this year compared to 2007.