Authorities believe that thousands of PCs belonging to UK citizens have been infected with malicious computer codes, including the infamous Zeus Trojan, enabling an organized criminal network to capture personal log-on details.
The gang is then accused of using the information to access bank accounts and fraudulently transfer funds to previously opened 'mule' and 'drop' accounts.
Several major world banks have suffered losses with around £6 million thought to have been taken from UK citizens in just one three month period although police say this figure is likely to "increase considerably".
The PCeU worked with the UK banks through its Virtual Taskforce gathering information and evidence ahead of making the arrests.
The 19 were arrested on suspicion of offences contrary to the Computer Misuse Act, Proceeds of Crime Act and the Fraud Act and are currently in custody for questioning. Two were also arrested on suspicion of possession of a firearm.
Detective Chief Inspector Terry Wilson of the PCeU, says: "We believe we have disrupted a highly organized criminal network, which has used sophisticated methods to siphon large amounts of cash from many innocent peoples' accounts, causing immense personal anxiety and significant financial harm - which of course banks have had to repay at considerable cost to the economy."