Online shoppers reported losing more than $550 million in 2009 due to Internet fraud, falling prey to a variety of increasingly sophisticated scams, according to a story in the Los Angeles Times that was based on a report by the Internet Crime Complaint Center.

The loss was more than twice that reported in 2008, according to the agency, a partnership of the Federal Bureau of Investigation and the privately funded National White Collar Crime Center. The center, based in West Virginia, tracks Internet crime around the world.

“Criminals are continuing to take full advantage of the anonymity afforded them by the Internet. They are also developing increasingly sophisticated means of defrauding unsuspecting consumers,” said Donald Brackman, the center’s director.

Part of the increase can be attributed to a change that allowed more cases to be included, but another possible factor was the increased use of the Internet, which has broadened the pool of perpetrators and victims, said Charles Pavelites, an FBI special agent.

More complaints were reported by California residents than by residents of any other state, the report said. Common fraud included the nondelivery of merchandise ordered through Web sites and “advance-fee scams,” in which victims were persuaded to make small payments to receive windfalls that never arrived, the report said.

Computer viruses capable of secretly downloading passwords and account numbers are also a problem, Pavelites said. Spread through e-mail attachments, the viruses allow criminals to steal from bank and credit card accounts.

In April 2009, the Internet Crime Complaint Center linked 103 cases in which victims reported paying for vehicles and motorcycles that did not arrive. The victims lost a combined $360,000 that was sent to a fraudulent financing center suggested by the seller, the report said. Consumers can take precautions to avoid being victimized by installing up-to-date computer firewalls and using only reputable payment centers to make purchases online, Pavelites said.