Fenland is currently being targeted by organised criminals posing as police officers to obtain cash.
DI Dave Murphy said there have been nine offences in last two weeks and on two occasions the elderly victims have handed over a large sum of money.
There were two more offences on Tuesday.
DI Murphy explained: “Elderly victims are contacted by phone by someone who pretends to be a police officer. He gives his badge details and invites the victim to phone him back to check he is a legitimate police officer.
“The offender doesn’t hang up, but stays on the line and pretends to answer the phone when the victim calls back, he then persuades the victim to withdraw a large amount of cash from their bank which he says the police will pick up from their home address by courier.”
DI Murphy emphasised: “The police will never ask members of the public to withdraw money from their bank. If you are contacted by these criminals then hang up and call Cambridgeshire Police and not the police force the caller is pretending to be from. This type of crime is occurring right across the country.”