ATM users across the area have been warned to be extra vigilant after an off-duty police officer spotted a hidden camera on a cash machine.
A secret lens had been installed on the machine but was incredibly difficult to spot without expert knowledge.
The device was spotted at the cashpoint by an off-duty special constable who has now issued a warning to others.
Police tweeted a picture of the ATM in London and wrote: "Off duty @MPSNewham Special Constable has sniffed out a covert camera recording the pin pad of this ATM in @MPSWestminster.
"This is why it is so important to #CoverYourPin when taking out cash."
The tiny camera was fixed to the receipt slot and is used to steal PINs from unsuspecting users, the Mirror reports.
Action Fraud said that after the fraudsters have a PIN they can steal the card and make a large cash withdrawal before the card is cancelled.
Thieves can sometimes also use a skimmer that fits over the card slot and is made to look like a normal part of the cash machine.
It is designed to copy the information on the magnetic strip of cards when it is inserted, leading to bank account fraud.
A card trap slides inside the real card slot so that when people finish using the machine, the card is swallowed and won't come out.
Fraudsters will watch and wait until the user leaves the area, remove the trap from the slot and take the card.
Cashpoint users are encouraged to check every cash machine they use, and to always cover the keypad when entering their PIN.
Anyone who thinks they have been targeted should call their bank straight away so it can't be used and report it to Action Fraud on 0300 123 2040.
