All Nippon Airways is introducing women-only lavatories on its international routes, joining Korean Air as the only other airline to offer such a service.

The ladies-only lavatories will come into service on 11 March on all ANA long- and medium-haul flights.

The move comes in response to “numerous requests from passengers for this service,” the company said in a statement.

Both women and men called for the airline to give them their own lavatories in a 2007 survey of customers, said ANA spokesman Justin Massey.

He said: “They didn’t list any specific complaints. It was just more a matter of general preference,” Massey added.

The planes will be fitted with “Women Only” signs on the doors of one lavatory, although the carrier said that in certain circumstances - for example, when a male passenger is unwell or when there are very few female passengers aboard the aircraft - then an announcement will be made to lift the women-only designation for the duration of the flight.

Women can still use any other lavatory.

While restricting men from using the women-only bathroom, the airline has spelled out exceptions to the rule, such when required for safety reasons or when a passenger is not feeling well or “when there are very few female passengers and the women-only designation has been lifted for the flight.”

However there are no plans to designate men-only lavatories.

In autumn, ANA also made an announcement encouraging passengers to use restrooms before boarding to reduce the weight of planes as part of its “ecological travel on the ground and in the sky” campaign.