About two-thirds of middle class people admitted offences such as not paying road tax and fare-dodging in the study by criminologists at Keele University.

Only 43% of those on low incomes confessed to one of the same practices.

The study also finds the middle classes guilty of "double standards" as 90% want action taken against law-breakers.

�14bn cost

Professor Suzanne Karstedt, from the Staffordshire-based university, said the results showed "it is the professional middle classes and high earners who commit most of these 'crimes' and are mostly involved in morally dubious practices.

"These are the people who see themselves as respectable but are part of a crime wave which is costing the UK around �14bn in fraud and forgery every year."

Percentage of all those surveyed who commit offences 33% - Keeping quiet when over-changed 22% - Paying cash in hand to avoid tax 14% - Fare-dodging 12% - Parking in a disabled spot 9% - Returning damaged items to shops 5% - Evading TV licence 4% - Not paying road tax

The study, which was carried out on behalf of TV Licensing, questioned 2,000 adults about practices including parking in a disabled bay, paying cash in hand to avoid tax and knowingly pocketing too much change.

Just under 65% of middle class people and high-earning professionals admitted at least one of the offences, compared to 55% of the general population and 43% of those on lower incomes.

But 91% of middle classes agreed that those who commit offences should "not be allowed to get away with it".

TV Licensing spokeswoman Vanessa Wood said: "There is an element of double standards here.

"Whilst nine out of 10 people demand action against those committing these offences, the majority actually admit to committing one of them."