Criminals are posing as police and stealing money from victims who believe they are helping an undercover investigation. UK Finance, which oversees banks' crime prevention, said that victims of the scam were losing large sums of money. These victims receive an unsolicited phone call from fraudsters claiming they are investigating fraud at a local bank branch. They are then tricked into withdrawing and handing over thousands of pounds. 'Nasty scam'

The criminals claim the bank is issuing fake bank notes, and asks for help in the "operation". The victim is asked to visit the branch, withdraw supposedly counterfeit cash and then hand it over for "analysis", having been assured the money will eventually be put back into their account. However, the fraudster disappears with the cash. The criminal tells the victim not to discuss the case with anyone in the branch so, despite being questioned by bank staff, the customer takes out the cash, convinced employees are part of a fraud.

SOURCE: