Fraudsters impersonating police officers have targeted a number of pensioners in Watford, Bushey and Three Rivers in a series of elaborate phone scams this week.

Hertfordshire Constabulary yesterday recorded six separate incidents of would-be scammers trying to con cash out of older people in the region.

In one attempt the fake ‘police officer’ told a 70-year-old man from Watford his bank was issuing counterfeit money to its customers. The offender said the man needed to go to the bank and withdraw thousands of pounds, which would then be collected by a courier and forensically examined.

The intended victim was suspicious of the call, prompting the fraudster to tell the man to hang up and dial 999 to confirm his identity.

The 70-year-old did this only to be reconnected with the conman, who had not hung up the phone. However, the man still was not taken in by the fraudster’s story and ended the call.

In a similar incident an 80-year-old man, also from Watford, was contacted by a caller pretending to be a police officer and claiming his credit cards had been used fraudulently.

The 80-year-old immediately said the caller should contact Watford police and hung up.

Giles Cooper, spokesman for Hertfordshire Constabulary, warned people in the area to be on their guard for suspicious calls.

He said: "If you receive a call you’re not expecting, you should be suspicious. Please remember the police and banks would: "Never ask for your bank account details or PIN number over the phone.

"Never ask you to withdraw money and send it to them via any means.

"Never ask you to send your bank cards, or any other personal property, via any means.

"If you are not happy with a phone call and are suspicious of the conversation you have with the caller then please end the call and contact police via the non-emergency number, 101.

"Remember, when reporting a suspicious phone call to police, wait at least five minutes before attempting to make the call, use a mobile, or test the line first by phoning a friend or relative, to ensure you’re not reconnected to the offender."

Similar incidents were also reported in Bushey, where officers confirmed a man in his late 60s was contacted by someone claiming to be from the police investigating fraudulent activity on the man’s account.

He was advised to dial 999 to confirm the information, but the man asked why it would be 999 as it isn’t an emergency. The man was then told to dial 101 instead but the man was already highly suspicious of the call and terminated it.

Another man was contacted by someone also claiming to be a police officer around 12.30pm. He was asked to confirm a number of personal and banking details, which the man refused to do and ended the call.

Also in Abbots Langley, a woman in her late 60s was called just after midday by a man who stated he was a police officer stationed in London.

He claimed someone had been arrested after they had been found using the woman’s credit card. He said that he would need the woman’s card details but that she should dial 999 first to confirm his identity. She hung up to do this but realised there was no longer a dial tone and so did not proceed with the call.

While in Watford, another woman in her early 80s was called at around 4pm by someone claiming to be from a specialist fraud department in London. The fraudster started to ask questions about her banking and personal details. At this point the woman challenged the caller and they ended the call.