AIB has warned its customers of a what it called a virus which is trying to obtain customers' credit card details and PIN numbers.
The bank has issued a warning on its internet banking site that a computer bug is causing a fraudulent screen to appear.
The bank says the virus is not attached to the AIB site.
A spokesman says that so far three customers using AIB's internet banking service have been redirected to the bogus site.
The bank says that the screen has also appeared while users were trying to access genuine internet shopping sites.
This type of scam has been called 'phishing', and redirects users to fake internet pages that imitate the real bank's site.
The hackers can then use the customer's details to make transactions, including money withdrawals.
A similar scam circulated in relation to the Citibank group earlier this year.
