Millions of consumers are switching banks and avoiding online shopping out of fear of having their personal data stolen by crooks and used in fraudulent activities, a research firm said Thursday.

Fully 6 percent of U.S. adults surveyed by Financial Insights said they had switched banks to reduce the risk of becoming victims of identity theft. In addition, the Framingham, Mass., research firm found that 18.3 percent of consumers had stopped shopping online for the same reason.

Translated into numbers, those percentages account for 12 million and 40 million adults, respectively.

The steady stream of media reports on identity theft has contributed to the fear among consumers, along with recent high-profile cases involving Bank of America and information gatherers ChoicePoint Inc. and LexisNexis.

The study, however, does not indicate whether people who have stopped shopping online would eventually return. In 2004, consumers spend $117 billion online, a 26 percent increase over the $93.2 billion spend in 2003, according to ComScore Networks.

"It's not necessarily black or white, when you're doing a big survey of consumers," Financial Insights analyst Sophie Louvel said. "But these statistics do show that (fear of identity theft) is impacting customers, and banks and retailers need to do something about it."

Both industries could do more to make online transactions more secure and develop better methods for verifying that people conducting transactions are who they say they are, Louvel said.

"The best defense is to be able to prevent a thief from actually using the data once they secure it," Louvel said.

Banks, in particular, may want to consider providing free services to help victims deal with the aftermath, such as correcting credit reports that may list the fraudulent activities. Recovery services available for a fee, such as Identity Theft 911, could act as models for the banks.

"They can be more proactive with identity-theft services that help victims recover," Louvel said.

Banks are beginning to look at helping identity-theft victims. BITS, a nonprofit industry group comprising 100 of the largest financial institutions in the U.S., is testing a pilot program that helps victims by streamlining the recovery process.