The software being offered by HSBC, which installs as a plug-in on most popular browsers, warns e-banking users if they their online banking credentials are used on non-SSL websites, offering them the option to customise the software if they wish.

Rapport, which was named the winner of the 2008 'best of the web' award from the Online Banking Report, works by securing communication between the customer and the bank during internet banking sessions, thereby protecting their personal information.

In use, the software warns customers if they are at risk of responding to a phishing attack, prevents trojans from capturing their details, and inhibits any interference with online communications – such as transactions – between the customer and the bank.

According to HSBC, which has been offering the Rapport download since earlier in the month, large numbers of customers have installed the plug-in on their PCs and Apple Macs,

The bank says the software protects customer data and prevents fraudulent activity by locking down browsers to prevent unauthorised access to web pages and to the confidential information that flows through the browsers.

Nick Staib, HSBC's digital security manager, said that download rates have surpassed the bank's most optimistic expectations.

"I am delighted that so many customers share our interest in keeping personal and banking details safe", he said, adding that Rapport is software that he uses himself and is happy recommending to friends.

When the RBS Group – which includes Natwest and Coutts – introduced Rapport for its e-banking customers last year, Gavin Coull, the bank's e-crime prevention manager, said that Rapport is fast to download and easy to install, but most importantly it allows us to quickly and effectively react to emerging threats.

"It also enhances the effectiveness of our existing card reader security. We're pleased that millions of customers are already benefiting from Rapport, with more downloading it every day", he said.