Skymark Airlines Inc.'s operations center at Tokyo's Haneda airport was inspected by the transport ministry after the nation's largest discount carrier canceled flights this month due to a pilot shortage.

The airline's staffing procedures are being checked to ensure there are no irregularities or other problems, Hirohiko Kawakatsu, an inspector in the Civil Aviation Bureau, said Monday.

Skymark has canceled 168 flights, or 10 percent of its scheduled services this month, and will cut a further 16 percent next month and 9 percent in August due to a shortage of pilots.