An estimated 3.6 million U.S. households — or about three out of every 100 — reported being victims of identity theft, according to a government study that counted misuse of someone else's cell phone, credit card or personal information.

The figures released Sunday by the Justice Department differ from findings of a previous government study that counted 9.3 million victims of the crime.

The department said the most frequent victims of identity theft were households headed by people age 18 to 24; those in urban or suburban areas; and those with incomes of at least $75,000.

The study was based on interviews with members of 42,000 randomly selected households over the last half of 2004, said Katrina Baum, a statistician with the Bureau of Justice Statistics.

The bureau defined identity theft in three ways:

—Unauthorized use of a credit card.

—Unauthorized use of an existing account such as a cell phone or bank account.

—Misuse of someone's personal information to open a new account, get a loan or commit some other crime.

Of the 3.6 million victimized households, the study said:

—An estimated 1.7 million discovered unauthorized use of credit cards during the six-month period. That is about 48 percent of households reporting identity theft crimes and 1.5 percent of all U.S. households.

—About 900,000 households experienced theft from other types of existing accounts, such as a cell phone account, bank account or debit-checking account. That is one-quarter percent of households with thefts and 0.8 percent of all U.S. households.

—Roughly 540,000 households said someone had misused personal information of someone in the home to open new accounts, get loans or commit other crimes. That was 15 percent of households reporting identify theft and 0.5 percent of all U.S. households.

The last category, and the rarest, is the one the financial services industry more often defines as identity theft.

"I think it's important to mentally distinguish between transactional fraud ... (like) the unauthorized use of a credit card, and identity theft, which involves the misuse of information to establish new accounts," said Anne Wallace, executive director of the Identity Theft Assistance Corporation. The industry-funded group helps victims resolve fraud problems for free.

An earlier report by the Federal Trade Commission found about 10.1 million people experienced identity theft in 2003 and 9.1 million in 2004. The Justice Department said the different results may be due to differences in the methods used to collect the data, the period of time considered and counting methods.

The department's study included questions on identity theft in a larger survey covering burglaries or other crimes a household may experiences. Some 6 percent of victimized households reported more than one episode of identity theft in the six-month period, and in those cases the survey only asked about the most recent incident.

The department estimated the loss to households due to identity theft at $3.2 billion. That total included money that may have been reimbursed by others, such as credit card companies or insurers.