Wharfedale residents are being warned about a fraud in which victims are persuaded to hand over their bank cards by people posing as police officers or bank employees.
The cards are then used to withdraw cash.
West Yorkshire Police is so far investigating about ten offences.
Detective Constable Mick Wilson, of the Economic Crime Unit, said: “The victim initially receives a call from someone claiming to either work for the police or a bank or building society saying that there has been fraudulent activity or another issue with their account.
“The caller will ask a series of ‘security’ questions, including asking for the PIN number.
“A taxi driver or courier will then call at the victim’s address and collect the card.
“The police, banks and building societies do not operate in this way and you should not disclose your PIN number to anyone, or hand your bank card over in this way.”