No Barclays online customer using its two-factor authentication security device has been hit by fraud, according to the bank.
The use of the Pinsentry devices, which were first distributed in November last year, has tripled as more customers make transactions online. It was originally advised for customers setting up payments out of their account to a third party.
The system provides two-factor authentication by providing a card reader which the customer must use to make transactions alongside more traditional passwords and memorable words.
A spokeswoman for Barclays said: "More than 1.5 million customers are now using Pinsentry and none of them have suffered any online banking fraud since its introduction."
The systems, which were initially sent to 500,000 customers, are now being used by many more as "customers changed their online habits," according to the spokeswoman.
Earlier this month Barclays offered all of its two million online banking customers a free internet security package.
The software, from Kaspersky, offers free anti-virus, anti-spyware, and anti-adware, along with a firewall, spam-filtering software and parental controls.