Credit-card group Visa International said cardholders must be vigilant even though a security breach in the United States would have very little impact in the Middle East.

MasterCard, another leading credit-card company, has said 14 million of its customers may have been exposed to the fraud, but Visa has yet to provide estimates.

"Visa International is aware that a third party payment card processor in the US has experienced a data security breach, resulting in the compromise of payment card account information," said Kamran Seddiqi, general manager of Visa International, Middle East. "As the vast majority of the compromised cards were US-issued, we anticipate very minimal impact in the Middle East," he said in a belated statement.

A security breach has exposed at least 40 million cards of various brands to potential fraud in the biggest such privacy violation. The fraud was traced to Atlanta-based CardSystems Solutions Inc, which processes transactions for banks and merchants.

"Visa will continue to work with financial institutions and law enforcement agencies to protect cardholders and investigate this breach," said Seddiqi. "Visa encourages cardholders to regularly monitor their accounts through regular statements and internet account access, and to notify their issuing bank of any unusual activity."

Banks in the UAE said there had been no complaints from cardholders.

"Banks are also taking protective measures and are investigating but, until now, we have not yet discovered anything unusual," the head of cards division of an Abu Dhabi-based bank said.