Emmanuel Mmaduike and Olawale Kashimawo, both 31, obtained thousands of business email addresses and passwords which they used to divert payments from companies to themselves, according to the UK National Crime Agency.
They were said to have operated from south-east London and spent the money on “a lavish lifestyle”.
Sky News reports that they hired a helicopter, drove “flash cars”, and “posed for photographs of themselves with wads of money, expensive watches and drinking champagne”.
Known as business email compromise (BEC), the operation involves the criminal impersonation of a senior executive and attempting to convince the victim to transfer funds.
Mmaduike was said to have played the role of accessing the victim’s email accounts and change invoices so that payments were directed to mule bank accounts run by Kashimawo.
His collaborator then laundered the cash by arranging withdrawals and international bank transfers which were carried out by other fraudsters.
The pair are believed to have carried out more than £1m of fraud and money laundering between April 2015 and November 2015, according to the NCA.
Mmaduike was jailed in March 2017 for six years and 10 months after he admitted money laundering and fraud.
He also admitted perverting the course of justice in relation to a sham marriage to a Dutch national.
Kashimawo was also jailed for six years and nine months after admitting two counts of conspiracy to commit money laundering.
Similar arrests have been made in Nigeria, one of the most recent being the by the Economic and Financial Crimes Commission (EFCC) in Abuja.