A Japanese train company has apologised after a train left just 20 seconds early and caused "severe inconvenience" to commuters.

The Tsukuba Express train was due to leave Minami Nagareyama station, a stop with rapid commuter services just north of Tokyo, at 9.44am on Tuesday (14 November). However, the service left at 9:43:40 – 20 seconds early.

A statement issued by Tsukuba Express later the same day said: "On November 14, at approximately 9:44 a.m., a northbound Metropolitan Intercity Railway Company (main office in Tokyo, Chiyoda Ward, President & CEO Koichi Yugi) train left Minami Nagareyama Station roughly 20 seconds earlier than the time indicated on the timetable. We deeply apologize for the severe inconvenience imposed upon our customers."

The statement also explained, according to the BBC, that the mistake happened because staff did not check the timetable carefully enough. It said: "The crewman handled the passengers on board after opening the door. After that... I closed the door without checking the departure time sufficiently."

Tsukuba Express added that no-one had complained about the early departure, but apologised nonetheless.

Japanese trains are world-renowned for their reliability and exact punctuality to the timetable, meaning commuters can arrive at the platform exactly on time for a train.

Delays are so rare, passengers can even be given a delay certificate to show their workplace or school if trains are delayed by just five minutes.