North Yorkshire Police says people across the county are being relentlessly targeted by a caller claiming to be Det Con Mason Greenwood from West Yorkshire Police.
There have been more than 20 reports of the ploy in the last two weeks alone and thousands of pounds have been lost.
North Yorkshire Police is again issuing an urgent warning to anyone receiving this kind of call to hang up immediately.
Stories given by the scammer include a claim that the victim’s grandson or nephew is in police custody and has possession of the victim’s debit or credit cards.
Another has been that there is a fraud investigation ongoing and the victim’s money is not safe in their current bank accounts.
The scammer will then ask people to move money from their account into another account for "safe-keeping" - but the reality is that the money is being stolen.
North Yorkshire Police Financial Abuse Safeguarding Officer, Andy Fox, said: “We have already issued a number of warnings about this dangerous scam but residents continue to be targeted and, although we all like to think that we won’t fall for it, scammers work very hard to manipulate and build trust with their victim.
"Unfortunately, thousands of pounds have already been lost to this fraudster and we want to do everything we can to make sure it doesn’t happen again."
The police say they will never ask you to transfer or withdraw money from your bank account or ask you to lie.
“We’d urge anyone reading this to please tell as many people you know about this scam," said Mr Fox.
"The more people who are aware of it, the less these unscrupulous individuals will succeed in stealing any more money from their victims.”
A message from the editor
Thank you for reading this story on our website. While I have your attention, I also have an important request to make of you.
In order for us to continue to provide high quality and trusted local news on this free-to-read site, I am asking you to also please purchase a copy of our newspaper.
Our journalists are highly trained and our content is independently regulated by IPSO to some of the highest standards in the world. The dramatic events of 2020 are having a major impact on many of our local valued advertisers and consequently the advertising that we receive. We are now more reliant than ever on you helping us to provide you with news by buying a copy of our newspaper.