Fraudsters have been using this tactic across the UK, however West Mercia Police have noticed an increase in Worcestershire.
The criminals often target older and vulnerable people and try to get them to transfer money or share their PIN information.
They will contact you to ask for your PIN or bank details, ask to withdraw cash to hand over to them for safe-keeping, ask you to transfer money out of your account for fraud reasons or send someone to your home to collect cash, PINs or cards.
A West Mercia Police spokesperson said: “We have received a recent increase in the number of reports of fraudsters across Worcestershire claiming to be from various police services around the country.
“These criminals are pretending to be police officers in an attempt to defraud people and scam them into handing over or transferring money, or sharing PIN information.
“This crime, known as ‘Courier Fraud’, has seen elderly and vulnerable people targeted. However, anyone can be a victim to this crime.
“We urge you to share this information about bogus callers with relatives, friends and neighbours who may also be at risk to the scams.
“We would also like to reassure our communities that we are investigating these crimes and want to hear from anyone who has been contacted in this way.”