U.S. Internet advertising surged 38 percent to a record $3.9 billion in the first quarter as marketers moved additional dollars to the Web, according to data released on Tuesday.

The Interactive Advertising Bureau and PricewaterhouseCoopers surveyed leading companies that sell advertising space online, including Yahoo Inc. (YHOO) and Google Inc. (GOOG), which are benefiting as consumers spend more of their media and purchasing time on the Internet.

"The momentum has continued to build in the Internet advertising space," said David Silverman, a partner at PricewaterhouseCoopers. "More and more advertisers are seeing the effectiveness of the medium."

The IAB and PricewaterhouseCoopers, which have tracked online ad spending since 1996, provide more detailed ad revenue analysis in the second and fourth quarters.

But the preliminary first-quarter figures indicate the strength of online advertising, which grew to a $12.5 billion industry last year from less than $1 billion in 1997.

First-quarter Internet ad revenue was up 38 percent from a year earlier and up 6 percent from the fourth quarter of 2005.

Silverman said the increase from the fourth quarter was notable because year-end advertising tends to be heavy to reach consumers during the peak holiday shopping season.