The British police foiled a plot to steal millions of pounds from Santander by controlling its computer system remotely.
Police have arrested twelve men in connection with the attempted crime, with four of them being charged with taking control of computers, following an operation by the Metropolitan Police's Central e-Crime Unit.
Serious crime investigator Mark Raymond said it was a sophisticated plot that could have led to the loss of a very large amount of money from the bank, and is the most significant case of this kind.
"I would like to thank our partners from the industry who have provided valuable assistance throughout this investigation," Raymond said.
The plot involved a fake maintenance engineer trying to install a keyboard-video-mouse (KVM), which is used to manage several computers at once, onto one of the bank's computers at south London shopping centre.
A Santander spokesman said the firm was made aware of the threat before the fake engineer tried to fit the device in a branch in Sirrey Quays, and had been working with police to monitor the threat.
He added: "The attempt to fit the device to the computer in the Surrey Quays branch was allegedly undertaken by a bogus maintenance engineer pretending to be from a third party.
"It failed and no money was ever at risk. No member of Santander staff was involved in this attempted fraud.
"We are pleased that we have been able, through the robustness of our systems, to prevent the fraud and help the police gather the evidence they needed to make the arrests."