A Tokyo subway operator and six major private railways launched a joint campaign Monday to stress the ban on mobile-phone use on trains during peak hours due to the danger of radio-wave interference with pacemakers.

The Teito Rapid Transit Authority, Tokyu Corp., Kinki Nippon Railway Co., Keihan Electric Railway Co., Hankyu Corp., Hanshin Electric Railway Co. and Nankai Electric Railway Co. are making on-board announcements telling passengers to shut off their mobile phones.