Rail firms will be forced to admit that three times as many trains are delayed than current figures show, as a new website will for the first time let commuters check when their train is just one minute late.

At present Network Rail data shows nine in ten (89.1 per cent) of trains arrive "on time", but this will fall to two in three (66.9 per cent) under the new measure, which deems a train "late" if it arrives 60 seconds after its due time.

Current figures deem a train service “late” if it arrives at its destination more than five minutes after its due time on a short journey or 10 minutes on a long distance route.

Last night campaigners said commuters had been misled over delays for years.

Anthony Smith, head of watchdog Transport Focus, said: “Train timetables need to be a work of fact, not fiction. So, it is good to see train operators reporting true on time performance to the minute at every station.”

It is expected that the website, which goes live in April, will be used by commuters who suspect their trains are regularly suffering mild delays.