The National Irish Bank has changed its online banking security system, meaning that its Mac customers must contact the bank immediately.

A report on MacInformation explains the change: the bank's new system relies on Microsoft's Active X technology, which means Mac users need to request a free code generator, which will produce the passkey each time a user logs onto the service.

"If you use Safari, Firefox (Windows or Mac) or ay other non-Internet Explorer browser, you need to phone 1890 812007 to order this code generator. It is a small credit-card-sized device which will generate a code for use on the bank's website. This is posted to the customer for free," the report explains.

The new service launches April 18.