The transport ministry said Thursday it is considering administrative penalties against West Japan Railway Co. over an incident in which a driver fell asleep at the helm of a bullet train.
Police meanwhile are investigating the case on suspicion of professional negligence and are questioning the driver and other people involved.
"We are considering taking measures against JR West, such as issuing a warning or punishing the driver," said Toshiki Aoyama, vice minister of land, infrastructure and transport. "(JR West) must enforce all-out measures for supervising (drivers') health, checking the way the roll call (is conducted) and the state of (drivers') mind."