Losses from online banking fraud hit a record £21.4m in the first half of 2008 - an increase of 185 percent on the previous year, says APACS.
According to the UK payments association, phishing attacks are to blame for the surge. In the first six months of 2007, 7,224 successful phishing attacks were recorded but this dramatically increased to more than 20,000 in the first half of this year.
"The increase is largely due to criminals targeting online banking customers through phishing and spyware scams - because the banks' own systems have proved difficult to attack," APACS claims.
However, the association warned that the losses "need to be seen in the context of increasing numbers of online retailers and ever-growing numbers of online transactions".
"From 2001 to 2007 this type of fraud went up by 204 percent while, over the same time period, the value of online shopping card transactions alone increased by 415 percent."