Credit card firms are set to resume operation later this week after three-month business suspensions for earlier massive data breaches, officials said Sunday, while their chiefs are expected to face heavy punishment soon.

According to the officials, the Financial Supervisory Service (FSS) will lift operation bans on KB Kookmin Card Co., Lotte Card Co. and NH Nonghyup Card Co. from May 17.

The three companies were ordered to suspend their business for three months from February over the leak of some 140 million customers' data.

The largest-ever data theft came to light in January when an employee from a personal credit ratings agency, the Korea Credit Bureau (KCB), was found to have stolen sensitive personal information, including resident registration numbers, bank account numbers and credit ratings.

"We decided to lift the three-month ban as scheduled, as the three card firms haven't conducted any wrongdoings or irregularities during the period," said an FSS official.

From next week, the card firms will be able to engage in card issuance services, credit-card loans and insurance business, according to the watchdog.

Industry data showed that they lost a combined 3 million customers during the suspension period, incurring a loss of 50 billion won (US$49 million) to Kookmin Card, 40 billion won to Nonghyup Card and 30 billion won to Lotte Card.

Apart from the business suspension, the FSS will also reprimand chief executives of the card firms as investigators discovered that the stolen data had come into possession of dealers of such information and were being circulated, fueling concerns the data would be abused by financial scammers.

“Their executives are expected to receive stricter punishments as the case is so grave," said the FSS official.

Industry insiders expect the FSS will demand resignation of the heads of the card firms. (Yonhap)