The suspects, one from Nigeria and two from Romania, were detained at a central London hotel last night by detectives from the Met’s Central e-Crime Unit (PCeU).
They were taken to a police station in the capital, where they are being quizzed on suspicion of conspiracy to defraud and money laundering
The arrests followed reports that more than 2,000 phishing pages, which mimic genuine banking websites, had been placed online to dupe unsuspecting victims into entering their confidential details.
A large number of accounts were then illegally accessed and had money withdrawn without the holders’ knowledge.
Officers working in partnership with investigators from the Serious Organised Crime Agency (Soca) also seized a number of computers which are being forensically examined.
Further searches are ongoing in London and the Midlands, Scotland Yard said.
Detective Superintendent Charlie McMurdie, head of the PCeU, said: “This is the first joint operation between the PCeU and Soca Cyber as we move towards full integration and inception of the National Cyber Crime Unit on October 1 2013.
“The dynamic nature and successful outcome of this operation, which has prevented distress and financial loss to numerous UK victims, clearly demonstrates the benefit of brigading resources and expertise in this increasing and specialist area of criminality.”