UK online banking fraud rose 12% in 2012 to £39.6m from £35.4m in 2011, according to research by consumer advice group Financial Fraud Action.
Financial Fraud Action said this increase was largely driven by fake websites which have tricked consumers into giving away their online banking login details.
Online banking customers are also being tricked into divulging their login details, passwords and other personal data over the phone to someone they believe is from their bank but is actually a fraudster.
Telephone banking fraud losses fell 35% to £12.6m in 2012 from £16.7m in 2011.
According to Financial Fraud Action, this reduction reflects the success of procedures used by banks to confirm customers’ identity, but has led to criminals focusing their efforts on accessing accounts online rather than over the phone.
Fraud losses on UK cards totalled £388m in 2012, showing a 14% increase from total fraud losses of £341m in 2011.
This increase follows three years of significant decreases, with fraud dropping to a ten-year low in 2011.
Financial Fraud Action said the 2012 rise was driven by crude scams designed to bypass security systems by duping consumers into handing over their own cards and PINs.
Another major factor is the use of UK cards in countries where security levels are lower than in the UK.
Detective inspector David Timmins, from the Dedicated Cheque and Plastic Crime Unit (DCPCU), said: "This latest set of national figures demonstrates the new frontline in the fight against fraud.
"As a consequence of more robust security features, criminals are resorting to low-tech deception crimes designed to dupe customers into parting with their cards, PINs and financial passwords."