Passcodes needed to enter secure areas at 16 Japanese airports and one in Guam have appeared on the internet after a virus infected a computer belonging to a Japan Airlines co-pilot, the airline said today.

The codes, which included those for Tokyo's Narita and Haneda airports and an airport in the US territory of Guam, are typically known to scores of airport workers who need to gain access to areas normally off limits to passengers, said Geoff Tudor, a spokesman for JAL in Tokyo.

Airline staff, particularly those on domestic routes, need to know a large number of codes because of the numerous airports served and typically have a list similar to that leaked, he said.

Upon learning of the leak the airports were notified of the need to change the codes. To date 12 of the airports have changed their codes and the others will do so soon, said Tudor.

JAL is not planning any disciplinary action against the co-pilot. "He was supposed to have these codes, he hasn't done anything illegal," said Tudor.

JAL has regulations regarding the downloading of sensitive corporate information to personal computers. However, the airport codes didn't fall within this category because they are so widely known among aircrews, ground staff, maintenance workers, cleaners and other airport staff.