Conmen are posing as police officers to dupe people into taking part in a fake undercover operation.
Members of the public are being phoned by someone posing as an officer saying they are investigating staff at a local bank branch.
As part of the scam, the individual is told to visit the branch and withdraw a substantial sum, often thousands of pounds, of supposedly counterfeit cash to hand over to the fraudsters for 'analysis'.
The victim is assured that the money will be deposited back into their account after the operation is complete.
However, once the money is passed over the fraudster disappears.
The scam has been designed to bypass bank security as the victims are duped into believing staff are involved in an alleged criminal activity.
As a result, despite being questioned about their withdrawal, the victim takes out the cash convinced that staff are part of the fraud.
In another version of the scam, the criminal convinces the victim to transfer money to a so-called 'safe account' to protect their funds from the 'corrupt' bank staff.
However, the account is in fact controlled by the criminal.
Police described it it is a 'particularly nasty' scam.
TOP TIPS ON HOW TO KEEP SAFE
► The police will never ask you to become part of an undercover investigation or for you to withdraw cash and hand it to them for safe-keeping;
► Be wary of any calls, texts or emails purporting to be from the police asking for your personal or financial details or for you to transfer money;
► Make elderly and vulnerable relatives and friends aware of the types of calls to watch out for and register them for telephone and mail preference services;
► Hang up the phone, answer none of their questions and call 101 or 999 if someone is on their way to your home.