A staff member of Japan Airlines helps customers at Osaka International Airport on the outskirts of Osaka, Japan, Dec. 26. AP-Yonhap

Japan Airlines (JAL) said on Thursday its systems returned to normal, with same-day ticket sales resuming, after a cyberattack delayed some domestic and international flights.

The attack began at 7:24 a.m., affecting internal and external systems, JAL said earlier. It temporarily shut down a router that was causing malfunctions and suspended ticket sales for flights departing on Thursday.

No customer information was leaked, however, the company said, and it suffered no damage from computer viruses.

ANA Holdings, Japan's other major air carrier, saw no signs of an attack on its systems, a spokesperson said.

American Airlines briefly grounded all flights for an hour this week, disrupting travel for thousands on Christmas Eve, due to a technical glitch involving network hardware. (Reuters)