A YouGov survey of 2000 adults, which was commissioned by the electricity company npower, found that around nine per cent of respondents believed they had been a victim of ID theft - the equivalent of six million people. The under 30s were found to be the most vulnerable group.

But the research found that despite the high number of incidents, many people are still not taking the necessary measures to protect their personal data. Around 22% were unaware that a utility bill could be used to steal a person's identity, and this figure rose to 28% among the under 30s.

Two-thirds of the under 30s also say they have shared personal data such as online banking passwords and PIN numbers with other people, compared to 40% in the 30 to 50 year age range and only a third of over 50s.

Figures from UK consumer credit industry body CIFAS show there were 137,000 reported cases of ID theft in 2005, but Professor Martin Gill, ID theft specialist and professor of criminology at Leicester University, says official statistics relating to cases of ID theft are not indicative of the true scale of the crime.

"It is relatively easy for a thief to steal someone's identity and as the research indicates, people aren't as cautious as they should be when it comes to safeguarding their own personal details and those of others. They are blissfully unaware of the dangers," says Gill.

Many victims only discover their credit rating has been adversely affected by fraudulent activity when they apply for a loan, credit card or mortgage.

According to the report, eight out of ten 18-29 year olds do not know their current credit rating and 59% don't know how to obtain it.

Commenting on the research Neil Munroe, chair of the identity fraud consumer awareness group and external affairs director at credit reference agency Equifax, says: "The report reveals that there is still confusion over how individuals check their credit reports. This is worrying as your credit report is a key tool in the fight against ID Fraud which can be easily accessed online."

Munroe urges consumers to take steps in order to protect themselves against the crime as "prevention is definitely better than cure".