About 12,000 local cardholders may be affected by the US credit card data leakage, Monetary Authority Deputy Chief Executive Raymond Li says, adding the risk of similar incidents in Hong Kong is low.

Mr Li told the Legislative Council Financial Affairs Panel today there are suspected unauthorised transactions involving 134 credit cards, totalling $740,000.

He said CardSystems reportedly breached security standards as it stored cardholders' information after providing authorisation and validation processes on behalf of merchants. Local cardholers may be affected if they purchase at US retail outlets either at the point-of-sale or online.

In view of the incident, local authorised institutions have contacted most of the potentially affected cardholders for card replacement. For those who cannot be reached, transactions conducted through their cards are monitored closely. Meanwhile, the authority has issued comprehensive guidance to authorised institutions and its specialists will conduct IT on-site examinations.

The authority has also required parties involved to re-assess the adequacy and effectiveness of controls over customer data security.

Mr Li said card issuers will bear the full loss incurred when faults have occurred in the terminals or other systems used which cause cardholders to suffer direct loss, and when transactions are made through the use of counterfeit cards.