Tesco Bank, which has seen many customers unable to access their accounts all week following a technical upgrade, has issued urgent guidance on how to make a popular browser work on its website.

Microsoft Internet Explorer 9 users have experienced significant problems when attempting to log in or update their security details on the Tesco Bank websites, leading to a flurry of angry comments on the web. Users commenting on the Computerworld UK website said they experienced better outcomes when moving to alternative browsers.

IE9 was made available to the public in March. Pre-release versions are also typically available before the date, and are widely used by businesses to make sure their websites will work.

On Microsoft's online guide to websites that do not work in IE8 or IE9, the vendor states that the problem only occurs because "some websites are designed for older browsers". It adds: "You may experience compatibility issues on these sites until they are updated for Internet Explorer 8 or for Internet Explorer 9.

Tesco today apologised "unreservedly" to customers as it issued the advice page for how to access the site on the IE9 browser.

"If you're finding Tesco Bank's website is not displaying or working correctly in Internet Explorer 9, you'll need to enable Compatibility View," the bank says on its advice page. This can be done by accessing the 'Tools' menu in the browser.

The site also offers advice on upgrading security details.

Computerworld UK readers yesterday expressed deep frustration that a standard internet browser failed to work on Tesco Bank's website.

"I would have hoped that Tesco would have had enough IT experts to prevent this meltdown," one wrote. "Tesco are treating their customers disgracefully!!" wrote another.

Some readers said they still experienced problems accessing the site on Firefox, especially with Private Browsing enabled, as well as experiencing trouble on Apple's Safari browser.

Chris wrote: "I did download Firefox and managed to get in to my account (I also had to download Flash V9 - God help anybody who doesn't know what they are doing). It sort of worked ok but the new level of security wouldn't let me move any money to my high street bank account without sending them a bank statement first."

One reader, ACB, said he had accessed his account using Google Chrome. "After days of trying unsuccessfully to access my Tesco Internet saver account I have now discovered that it appears to work using the Google Chrome internet browser," he wrote. "I thought this may be of interest to those of you who desperately need access to your money to pay bills."