Today's arrests follow an investigation into an apparent online scam whereby £1 million was siphoned off the accounts of customers of two banks.
The alleged scam involved emails, that appeared to be from the banks, containing "malware" which corrupted the recipients' computers.
T/DCI Jason Tunn of the Metropolitan Police's Cyber Crime Unit said he suspects they are dealing with an "international and organised crime targeting a number of bank customers in London and across the UK".
"The victims have been hoodwinked by malware-carrying emails purporting to be from their banks, and subsequently had money taken from their accounts," he said.
More top news
Donald Trump has indicated he does not intend to block the release of thousands of secret files about the assassination of John F Kennedy.
Storm Brian will track off into the north sea later tonight. Blustery tomorrow.
The Evening Standard airbrushed the singer's braids from its front cover.