FAKE cops are attempting to con people into handing over card and pin numbers across Essex.
At least 21 people were targeted in 24 hours with one man from Dedham, who fell for the fraudsters 'scam, losing £2,500.
The con artists call people and claim to be from Essex Police or the Metropolitan Police.
A spokesman for Essex Police said: "Twenty of the intended victims quickly realised they were the targets in a long-running scam but a man in Dedham was tricked into handing over credit and bank cards.
"About £2,500 was withdrawn from a local ATM machine before the cards were stopped."
The latest spate took place for 24 hours from Monday night.
A spokesman for Essex Police added: "In all cases the caller claimed to be either a detective from either the Metropolitan Police or Essex Police.
"Similar false names were used by the callers but their stories varied from claims their victims’ bank cards had been cloned to claims suspects had been arrested in possession of stolen bank cards."
Det Chief Insp Paul Maleary, said: "These criminals are having a significant impact on some of the most vulnerable members of our society and sadly no individual is immune from this type of fraud.
"These thieves try different tricks to encourage people to hand over bank details or large sums of cash.
"Fortunately our intensive media campaigns warning of this scam have been working well and the majority of people quickly hang up or tell the tricksters to go away in no uncertain terms.
"But one successful crime out of 21 attempts is one too many and we will continue to issue these warnings as long as these crimes continue."
Essex Police is working with five other forces to combat the fraudsters.
Mr Maleary said: "We urge all relatives and friends of elderly people to make sure that they are extremely wary of any callers claiming to be police officers or bank officials who want bank cards, PIN number or large sums of cash which they claim needs to be forensically examined.
"All their claims are absolute rubbish because the police and banks would never ask for details over the phone then send a courier to collect cards or cash.”
In the past 15 months 700 thefts or attempted thefts have been reported in Essex.
More than 100 people have been conned out of more than £355,000 in total.
Six people have been arrested in connection with the investigation.