Police are fighting a new wave of middle-class fraudsters who have netted millions of pounds from British victims amid the recession, a senior officer has warned.

Mike Bowron, commissioner of City of London Police, said his officers were increasingly arresting professionals who have “exploited their position for personal and illegitimate financial gain”.

The suspects include lawyers, accountants and insurance brokers, many of whose scams were exposed by the credit crunch as investors tried to get their money back.

Mr Bowron said the number of frauds reported to his force has risen by 72 per cent in the past financial year.

While independent academics put the value of frauds in Britain at around £14 billion in 2005, Mr Bowron said he believed the true figure was now around £200 billion.

One of the biggest investigations on his force's books is an £80 million Ponzi-style investment fraud which is now thought to have claimed 750 victims, including former England cricketer and Strictly Come Dancing star Darren Gough.

Another high-profile case centres on an alleged £200 million mortgage fraud.

In many cases, the victims were “well-educated, confident investors” who were conned by plausible graduates taking part in sophisticated scams.

Mr Bowron, whose force has national responsibility for investigating economic crime, will outline the scale of the problem tomorrow at the National Fraud Forum conference in Buckinghamshire.

He told the Daily Mail: “We have got something like 6,000 individual victims on our books at the moment.

“The reasons for that are that we have gone looking for fraud, and the consequences of the recession.

“It is a whole combination of mortgage fraud, mass marketing fraud, Ponzi-type fraud, insider fraud and insurance frauds.”

He added: “I have a concern that some of the impact of the recession was not caused by the behaviour in foreign markets, but by a lack of control in our own.

“This is shown in the number of staff my teams are arresting for insider fraud and the number of lawyers, valuers, accountants and insurance brokers who have exploited their position for personal and illegitimate financial gain.”

Mr Bowron said officers have reported a sharp rise in cases of middle-class investors being cold-called by bogus stockbrokers and persuaded to buy worthless or non- existent shares, or to buy genuine shares at vastly inflated prices.

He described offenders as “generally young, educated Britons”.

His 200 specialist investigators have identified 70 organised crime groups involved in fraud. In many cases, they had previously robbed banks or dealt drugs.

Mr Bowron said they had been attracted to fraud by the knowledge that it was lucrative and the risk of being caught was low.