South Korea's transportation giant Hanjin Group said Monday one of its servers suffered a malfunction overnight due to a problematic power supply, leading to delays in some 40 flights from operators under its wing.

Hanjin, which operates Korean Air and Jin Air, said its subsidiaries' Web sites and mobile applications were paralyzed due to technical issues which were normalized as of 4:20 a.m. 

The group said the problem was not caused by cyberattacks or ransomware. It marks the first time that Hanjin suffered a complete shutdown of its server throughout the group.

The delay came as check-in procedures had to be conducted manually by its staff, including issuing boarding passes and handling luggage. A Korean Air flight from Incheon to Bali was delayed by more than 12 hours.

The failure also prevented customers from purchasing tickets or changing flight schedules.

South Korea's land ministry said it will urge the company to come up with efforts to prevent the recurrence of the issue for passengers' convenience.

The groupwide server failure created problems for around 20 affiliates, although only consumers of Korean Air, Jin Air, and Hanjin Transportation were affected, as the accident took place early in the morning. (Yonhap)