As the collapse of Barings Bank shows, fraud is usually committed by one of a firm's own trusted and respected colleagues.

Britain's oldest merchant bank collapsed in February 1995 because of massive losses run up by Nick Leeson, a rogue trader whom the bank's top-brass thought was running a highly- profitable arbitrage operation in Singapore.

Instead, Leeson was making huge losses but was hiding them behind what was described as a "complex and systematic process of deception and false accounting". Most fraud offences are committed by management, a new fraud survey from KPMG has found.

Why are people often caught unaware when somebody is accused of fraud?

Because it is usually the colleague who is known to be helpful, polite and inconspicuous.

But most importantly, it is the colleague that enjoys the absolute trust of both superiors and colleagues, according to the findings from the Profile of a Fraudster Survey 2007.

"Over 60 per cent of the perpetrators are members of top management," said Andrew Brown, director of KPMG Forensic in Ireland.

"Senior managers have access to confidential information, and due to their position, it is easier for them to bypass internal controls and inflict greater damage to the company overall." And that damage, in financial terms, can be extremely severe, according to Brown.

"Our experience here in Ireland and across Europe, the Middle East and Africa shows that both large and small businesses can be affected by this and suffer considerable losses."

Just over 70 per cent of fraudulent transactions cost more than €100,000 each.

"And two-thirds of fraudsters carry out 10 or more such transactions," said Brown. "So, even for a relatively small-scale fraud, companies are losing six- or seven- figure sums."

In most cases, the affected companies have to bear the losses themselves, according to Brown.

"Companies rarely succeed in making good the financial damage," he said. "This is exacerbated by the fact that the issue of compensation usually takes several years to clear up and there is a significant cost in management time in investigating the incident and putting in place better controls.

"Prevention is always a more cost efficient and cost effective means."

The KPMG survey indicates that the typical fraudster is male and between 36 and 55-years-old.

"By the time he starts profiting from his illegal means, he has usually been employed by the company for six or more years. He typically works in the finance department, and commits the deed alone.

"He is driven to crime by a desire for money and by the availability of the opportunity," said Brown.

Opportunity, motive and rationalisation - the fraudster's internal dialogue that provides self-justification for his or her actions - are the key factors behind what is known as the fraud triangle.

"The findings reinforce the notion that the overriding motivations for white-collar crime are greed, opportunity and the pressure to meet budgets and targets," the survey concluded.

"The last two reasons particularly should ring a warning bell and raise the awareness of employers because they provide at least one aspect of the fraud triangle and offer a reason for a second one."