According to Great Northern rail, the low speed derailment of an empty train at Welwyn Garden City late last night is causing disruption to journeys between Stevenage and London Kings Cross and Moorgate.
As a result of the incident, the company said, one of the four platforms at Welwyn Garden City is out of action and Great Northern train services using the station will be delayed throughout the day with the possibility of short notice cancellations and trains running with fewer carriages than normal. Trains are typically running 10-15 minutes late through the area.
The company said the train will be rerailed later today.
"Our engineers are assisting the train to enable it to move," the rail operator said. "Whilst this is ongoing, there will be some cancellations and delays. We are sorry for the problems this disruption will cause."
Great Northern warned that the disruption is likely to carry on until the end of service today.
A spokesman for Great Northern said: “We sincerely apologise to passengers for any delay to their journeys. Anyone who experiences delays should visit our website for information for information on how to claim compensation.
“A full investigation into the incident will be undertaken."