Thousands of air passengers in Japan saw their flights cancelled or delayed on Sunday after computer system trouble at All Nippon Airways (ANA) led to problems with the airline’s check-in system nationwide.

Most of the problems occurred at Tokyo’s Haneda airport, which is the main domestic airport serving the Japanese capital. A total of 53 flights were cancelled and 259 flights were delayed by more than 1 hour, Rob Henderson, a spokesman for ANA, said Sunday evening. The problems affected more than 51,180 passengers.

Airline executives apologized for the trouble at a news conference.

The problem occurred in communications between a server and check-in terminals at airports and was rectified at of 11a.m. local time (2a.m. GMT) but as of Sunday evening the exact nature of the glitch had not been identified.

In May last year problems in the link between ANA’s main host computer and the servers that connect to the check-in terminals caused the cancellation of 130 flights and the delay of 306 flights. Around 69,300 passengers were affected by that problem.