Serious fraud against UK banks has hit a record high with the crime costing more than £350m during the first half of this year.

KPMG's Fraud Barometer showed that a total of more than £630m worth of fraud went to court across 128 cases, which is a significant rise compared with £421m across 91 cases in the preceding six-month period. Of the £630m, more than half – £350m – was against financial institutions. More than half of the latter were carried out by organised gangs.

Worryingly, KPMG says that the full impact of the credit crunch on the rise in financial fraud may not be seen for at least another six months as businesses scrutinise their operations during tough times.

The report stated: “Fraud against banks totalled more in six months than in any previous entire year of the 20-year history of KPMG's Fraud Barometer. Previously, the highest level of fraud against the financial sector was £200m in 1998.”

High profile cases such as an alleged £220m attempt to hack into Sumitomo Matsui Banking Corporation's systems and a £70m attempted fraud within HSBC's securities services division influenced the findings. But these aside, there was at least £60m of banking fraud brought to court during the first half of the year; in the whole of 2007, the figure was £37m.

Hitesh Patel, partner at KPMG Forensic, called the trend “worrying”. He added: “Fraud remains extremely prevalent in the UK with professional gangs accounting for over two-thirds by value, ranging from investment stings to trading scams, card fraud and money laundering.

“Banks are working extremely hard to protect themselves and their customers from fraudulent activity, but the signs are that organised criminals and syndicates have been relentless in their efforts.”

He went on to warn that mortgage fraud was on the up – there were nine cases in the first half of this year totalling more than £20m whereas during the whole of 2007, there were only 10 cases, worth just £3.7m.