Financial authorities will announce details regarding the cause of a recent data breach at Lotte Card, as well as the scope of the damage, later this week.

Financial authorities and industry sources say the Financial Services Commission and the Financial Supervisory Service are in the process of verifying the scale of the data breach, as well as the number of impacted cardholders.

Lotte Card, which has nine-point-six million members, initially said one-point-seven gigabytes of data had been stolen during the incident. 

Authorities have since verified that far more was seized, including cardholders' names, contact information and transaction records.

After the investigation results are announced, the card company plans to issue a public apology, compensate impacted users and take steps to prevent recurrence.
 
Hackers breached Lotte Card's online transaction server using malicious code on August 14 and 15. The company came under fire after failing to report the incident until two weeks after it took place.