Four men have been charged over an attempt to take control of computers at a bank branch to steal millions of pounds, Scotland Yard said.
Police thwarted the cyber gang after one of the plotters allegedly posed as an engineer to fit a computer in a branch of Santander with a ''keyboard video mouse'' device that allowed them to transmit its desktop contents.
It is alleged the gang tried to use the gadget to take control of all the computers at the branch in Surrey Quays shopping centre in south-east London, but the attempt failed and the Spanish bank said they were unable to steal any money.
Lanre Mullins-Abudu, 25, from Putney; south-west London, Dean Outram, 34, from north-west London, Akash Vaghela, 27, from Hounslow, west London, and Asad Ali Qureshi, 35, from south-west London, have been charged with conspiracy to steal.
They will appear at Westminster Magistrates' Court later. Eight other people have been bailed to a date in mid-November pending further inquiries, police said.
Searches were carried out by police at addresses in Westminster, Hounslow, Hillingdon, Brent and Richmond, and also in Slough, where property was seized.
Detective Inspector Mark Raymond from Scotland Yard's Police Central e-crime Unit (PCeU), said: ''This 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 that we have come across.
''I would like to thank our partners from the industry who have provided valuable assistance throughout this investigation. 'The PCeU is committed to tackling cyber-crime and the damage it can cause to individuals, organisations and the wider economy.''
Santander said no member of staff was involved in the attempted raid. A spokesman said: ''Like all high street banks, Santander works very closely with the police and other authorities to help prevent fraud. 'Through this co-operation, Santander was aware of the possibility of the attack connected to the arrests. The attempt to fit the device to the computer in the Surrey Quays Branch was 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."