Over the last few days the PCeU, working with the MPS Territorial Support Group and the Irish Garda, has executed five search warrants in London and an address in Navan, County Meath, Ireland.
The raids resulted in five men and one woman being arrested on suspicion of conspiracy to commit online banking fraud and Computer Misuse Act offences. All six are now in custody in London.
The PCeU says the arrests are part of Operation Dynamophone, an investigation into a network believed to have systematically obtained large quantities of personal information, such as online bank account passwords and credit card numbers.
The gang is believed to have acquired the information through phishing, sending large quantities of unsolicited spam e-mails, directing victims to spoof Web sites purporting to belong to legitimate banks.
Police enquiries suggest more than 10,000 online bank accounts and 10,000 credit cards have been compromised. The crooks attempted bank account take-over fraud worth £1.14 million, with £358,000 stolen successfully, say authorities.
Detective Inspector Colin Wetherill, PCeU, says: "A great deal of personal information was compromised and cleverly exploited for substantial profit. By disrupting the operation we have hopefully prevented further loss to individuals and institutions across the UK.