Up to 3,000 Irish people with Visa and Mastercard credit cards have been alerted that their details may have been compromised and they will be issued with new cards by their banks.

The notices are part of a global alert sent out by the two large credit card issuers following what was described as an "internal breach of security" at an un-named US merchant. The incident could have affected cardholders who used their cards in the US 12-18 months ago. The breach is being investigated by international police authorities.

A spokeswoman for Visa said it was closely monitoring the situation.

"Visa will work with our members and law-enforcement officials to take whatever steps are necessary to protect Visa cardholders," the spokeswoman said.

She would not disclose which US merchant was affected by the security breach.

AIB, Bank of Ireland and Permanent TSB have written to customers whose credit card numbers could have been compromised, explaining that they will revoke their cards and issue new ones. The two big banks have each written to around 1,000 customers and Permanent TSB said that about 100 customers had been contacted.

Other financial institutions, such as National Irish Bank and Ulster Bank, have yet to contact customers that may be affected.

A spokeswoman for AIB said that it had decided to close these accounts on foot of the warning from Visa.

Mr Eddie Ryan of Bank of Ireland's credit card division said that, while it normally issued new cards within 48 hours, the summer months were the peak times for dealing with lost and stolen cards and it might take up to 72 hours at most for customers to receive a fresh card.

"Customers may be inconvenienced for a very short period," he said.

These customers will not have to pay another 40 in stamp duty on these cards and are being treated as if they are cards that are being re-issued.

Mr Ryan said these alerts were quite common and that financial institutions regularly notified customers where they believed their details might have been compromised.

The bank is making every effort to contact cardholders who may already be abroad and using these cards. Mr Ryan said, in these circumstances, Visa would issue a notice that would require a retailer to contact one of its centres to validate the cardholder's identity when these cards were presented.

The banks are advising customers to check their statements and any unfamiliar transactions should be queried directly with them. So far, none of the Irish financial institutions has said it has received specific queries relating to this particular alert.

Financial institutions can fully investigate all transactions and can ultimately show customers a copy of the date, time, amount, location and name of the retailer that processed this payment.

Most banks will allow customers to suspend paying any amount that is being investigated without incurring any additional charges or interest payments.