Thousands of online banking customers have had their accounts drained by a sophisticated new computer virus, internet security Experts say the virus represents a new level of sophistication
Around £675,000 was taken from a "large UK financial institution" over the last month with 3,000 customers hit - and the attacks are ongoing.
Online security firm M86 Security Labs said the customers were infected with a Trojan virus - which cannot be detected by traditional anti-virus software - while browsing the internet.
The Trojan, known as a Zeus v3, copies the passwords and usernames of customers' online details and transfers their funds to a different account.
It then gives the victim of the virus a false bank balance screen so they are unaware the cash has been taken.
M86 said the virus is potent because it has been carried on legitimate websites located in the UK and not confined to porn and gambling hubs.
The online security firm, based in California and Britain, uncovered the fraud when it penetrated the criminals' command server, based in Eastern Europe, and found a list of all the cash transfers.
The company said the cyber criminals had modified the Zeus virus, which is one of the most popular type of Trojan used by fraudsters, taking online hacking to a "new level of technical sophistication".