A bullet train running at a speed of 280 kilometers per hour had a door open during its journey from Sendai in northeastern Japan to Tokyo on Wednesday, but no passengers were injured, its operator East Japan Railway Co. said.

The incident in the morning lasted 40 seconds, with the door being completely open at one point, and is a rare occurrence for the Japanese shinkansen known for its safety and punctuality.

The problem was caused by a cleaner who forgot to close the car's device that manually opens and closes doors, the train operator said.

(File photo)

The conductor of the Hayabusa No. 46 bullet train made an emergency stop inside a tunnel in Shibata, Miyagi Prefecture, after seeing indications the ninth car's door was open. The train resumed its journey 15 minutes later after a checkup.

The crew did not notice the cleaner's mistake as the door was closed when the train left Sendai at 10:15 a.m. It is thought to have opened later.

Around 340 passengers were aboard the train but nobody was standing near the door.

The bullet train arrived at its final destination 19 minutes late. The problem delayed seven shinkansen services up to 28 minutes, affecting around 3,300 passengers.

The transport ministry urged JR East, which initially said the door was closed, to prevent a similar incident.