Organised gangs of criminals are posing as temps to gain access to private information in the banking industry, according to a senior police officer.

Detective chief superintendent Ken Farrow, who heads up the economic crime unit at the City of London Police, said that when criminals were installed at a bank they approached staff and offered money for account information.

But they then blackmailed staff, forcing them to continue passing on the information or carrying out fraudulent transactions.

“There is a lot of temptation in banking and these employees are potentially vulnerable,” said Farrow. “They think they can do it just once. Invariably it is those people who get caught and end up in prison, while the people who are managing it get away.” Farrow believes the pressure and competitiveness of banking causes managers to find staff, who are sometimes unvetted, quickly.

Farrow admitted that of the 350 fraud cases he is currently working on “a very significant number” involved insiders.

However the industry trade body the Recruitment and Employers Confederation hit back at claims temporary workers were to blame for any alleged fraud.

Tom Hadley, director of external relations, stated: “We will be contacting the City of London Police as a matter of urgency to find out the basis of their statements regarding temporary workers. It must be remembered that without temps, the finance and banking industry wouldn’t operate and would be far less competitive.”