Qatar's largest bank has acknowledged that some purported customer data disclosed online may be authentic and says it has hired an outside expert to review potential vulnerabilities to its computer systems.

Qatar National Bank last week said only that it was investigating "an alleged data breach" after what appeared to be personal details about thousands of customers were posted online. Several customers reached by The Associated Press confirmed that their personal information was authentic.

The bank said Sunday that "some of the data recently released in the public domain may be accurate," adding that some data comes from other sources.

The files release online in many cases contained bank customers' bank logins, passwords, security questions and answers, credit card numbers, Qatari national identification numbers, phone numbers and email addresses.