Setting identity theft aside, Internet-related scams rose to 53 percent of consumers' fraud complaints filed with the agency in 2004, up from 46 percent in 2002.
Such fraud accounted for 39 percent of all consumer complaints filed with the FTC, followed by Internet auction fraud, which made up 16 percent of total complaints, and shop-at-home and catalog sales with 8 percent.
Not counting ID theft cases, 35 percent of the fraud cases were initiated by an e-mail message, consumers reported, while 22 percent started at a Web site.
(Consumers usually report ID theft before they know the full extent of their monetary loss, the agency said.)
"We use these complaints every single day to help identify and target our cases.
Nevertheless, a separate survey recently found that the steep rise of identity theft cases may be leveling off.
According to the FTC, the most difficult to detect and often most expensive identity-theft cases -- where entirely new credit accounts are created based on a victim's identity -- declined as a percentage of ID theft complaints.
New account fraud was about 17 percent of all ID theft cases reported in 2004, down from about 19 percent in 2003 and 24 percent in 2002.
But other types of ID fraud increased: The percentage of complaints about electronic fund-transfer scams, mainly due to the theft of debit cards, grew to almost 7 percent of complaints in 2004, from 3 percent just two years earlier.
The metropolitan areas with the highest reported per-capita rates of ID theft were Phoenix/Scottsdale, with 182.2 complaints per 100,000 people; Riverside/San Bernardino, Calif., with 166.6; and Las Vegas/Paradise, with 163.8.
Andrea Coombes is a reporter for MarketWatch in San Francisco.