Identity Theft: Identities sold online for £80

Once stolen, the average identity yields online fraudsters around £15,000, researchers found.

Individual pieces of stolen data are available for as little as £5.

A study for Get Safe Online Week found one in five people use the same password for all their internet logins, leaving them wide open to hacking.

Half those surveyed did not update their anti-virus software often enough.

And nearly a quarter did not have any protection against spyware.

Tony Neate, managing director of GetSafeOnline.org, said the costs of protecting yourself online were relatively small compared to the potential losses from having your identity stolen.

He said: "We are actively encouraging more people to go online, but in doing so, to ensure that they are safe and secure.

"If internet users invest a relatively small amount of time and money in ensuring they are fully protected and up-to-date, the risk of such financial loss is almost negligible.

"To install the essential software and learn about the key safety measures takes a matter of a few hours - a small but worthwhile inconvenience compared to the potential loss."

Identity fraud affects around 100,000 consumers every year. The level of online banking fraud has doubled from its 2004 level and cost £22.6 million last year, according to the payments association Apacs.