Train services in and out of London Kings Cross, one of the country's busiest terminals, have been cancelled tomorrow because of overrunning Network Rail engineering works.
Sources said that the station would effectively be closed throughout the day due to delays to works north of the station.
East Coast Trains said customers would need to start or finish their journey at Finsbury Park in north London, with at least one change of train.
A reduced service to and from the station will go ahead as planned on Sunday, with trains leaving up to 20 minutes earlier than normal from King's Cross.
East Coast spokesman, Paul Emberley, said: "Network Rail has apologised to passengers for the inevitable delays to their travel plans on Saturday as a result of the overrunning engineering works.
"East Coast is particularly sorry too for the inconvenience to its customers as a result, on what we know is an already very busy travel day immediately following the Christmas break.
"For customers intending to start or finish their journey at King's Cross, consideration should be given to deferring travel plans to either Sunday or Monday.
"We're working hard over the holiday period to make the necessary adjustments to our timetable as a consequence, and to provide as much information as we can."