Almost a quarter of a million US consumers complained of being targeted for identity theft in 2004, official figures suggest.
Identity theft fraud is on the rise
The Federal Trade Commission said two in five of the 635,173 reports it had from consumers concerned ID fraud.
ID theft occurs when criminals use someone else's personal information to steal credit or commit other crimes.
Internet auctions were the second biggest source of fraud complaints, comprising 16% of the total.
The total cost of fraud reported by consumers was $546m (£290m).
The report marks the fifth year in a row in which identity fraud has topped the table.
The biggest slice of the 246,570 ID fraud cases reported - almost 30% - concerned abuses of people's credit.
Misusing someone's identity to claim new credit cards or loans comprised 16.5% of the total, with almost 12% coming from false claims on existing credit.
Another 18% came from attempts to rip off people's bank accounts, while 13% of cases concerned attempts to defraud employers by abusing someone else's identity.
Outside the field of ID theft, 53% of the near-400,000 complaints were internet-related.
Among the 100,000 internet auction complaints, the failure of sellers to deliver or the supply of sub-standard goods were the most common woes reported.
Catalogue and home-shopping frauds were next in line, accounting for 8% of total complaints, while concerns about internet services and computers - including spyware found on people's PCs and undisclosed charges for websites - amounted to 6% of complaints.