They have provided the following advice:
Never give out personal information about your bank account to anybody over the phone. Police and banks will never ask you to give out personal details such as account numbers or PIN numbers.
If someone calls claiming to be a police officer, ask for their identification number and police force. Hang up and call 101 using a different phone. If you can't use a different phone, wait at least five minutes before calling back. A genuine police officer will not mind waiting while you check.
Fraudsters will keep the line open and have been known to play ringtones, hold music and a recorded message down the phone so the victim believes they are making a call to a legitimate number. Ensure you can hear a dialling tone before calling police or use a friend or neighbour's telephone instead.
If you have given out information which could compromise your bank account security in any way, call your bank to cancel your cards as soon as possible.
Never hand over money to someone at the door to be sent off elsewhere.
We would urge the public to check on their vulnerable friends and family to ensure they are aware of how these scams may operate and how best to protect themselves.
If anyone has received a similar type of telephone call or has any information about these incidents, please contact Norfolk Police on 101 quoting ‘Operation Radium’.
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.