Total U.S. ad spending is expected to increase just 2.6 percent this year, according to a new forecast by TNS Media Service.

Although the media service estimates that ad spending rose 3.8 percent in 2006, the $153 billion projected for 2007 spending would be the smallest gain since 2001. The forecast has network TV rising 0.6 percent, spot TV falling 2.8 percent, cable network TV up 4.7 percent and syndication up 6.6 percent.

TNS expects advertising on the Internet to grow 13.4 percent.

“Our outlook for 2007 is tempered by the absence of two biennial advertising events, the Olympics and federal elections, which tend to contribute an incremental 80-100 basis points to growth rates,” said Steven Fredericks, president and CEO of TNS in a statement released Monday. “More significant, we expect (the) share of total ad spending will continue to shift away from the Top 100 marketers, as media fragmentation enables more brands with smaller media budgets to participate in the market, while concurrently helping dampen media price inflation.”