Hundreds of millions of stolen usernames and passwords from accounts including those held on Gmail, Hotmail and Yahoo are being traded by Russian criminals.
Anyone with an account on one of the services may want to consider updating their details.
The information is according to an investigation by news agency Reuters, which has spoken to Alex Holden of US company Hold Security.
He said research had unearthed millions of account details being bought and sold in Russia - including 40 million...
