An elderly man in Harrogate was fleeced of £3,000 after being telephoned by criminals claiming to be from the fraud squad yesterday.
The gang tricked the pensioner into withdrawing cash by telling him his bank account was being targeted by Romanian criminals, North Yorkshire Police said.
A bogus officer kept the victim on the phone, saying the cash had to be checked to see if it was counterfeit, while another man from a fake courier agency turned up at his house to collect the money.
The fraudsters used false names including PC Mark Lawrence and Detective Sergeant Mark Douglas in the elaborate fraud, police said.
In a second incident yesterday, an elderly woman was telephoned by a bogus official claiming to be "Sergeant Wiggen" from New Scotland Yard.
She and told there was suspicious activity on her account and that she needed to go to her bank and withdraw £17,000.
The withdrawal was blocked by bank staff who told the police.
PC Amanda Hanusch-Moore from North Yorkshire Police’s Harrogate Neighbourhood Policing team said: “These heartless fraudsters are sophisticated and well-rehearsed and whilst they typically prey on the elderly, any one of us could fall victim to their deceptions if we are not vigilant.
“It is important to remember that the police or your bank will never ask you to withdraw or transfer money from your bank account, even to aid an investigation.
“If you receive a call of this nature or have any suspicious at all, please be reassured that it is okay to hang up the phone and end the conversation."