Train services on the West Coast Mainline have been disrupted due to a signalling fault at London Euston station.
Virgin Trains running between Manchester Piccadilly are among the affected routes.
Some services have been cancelled, while others are being delayed or revised.
Passengers are being warned journeys may take longer this morning and it is not clear when the disruption will clear.
Read more of today's top stories here
The fault, near Queens Park, means Virgin Trains and London Northwest Railways services cannot run to and from London Euston.
Trains are terminating at alternative stations.
Virgin Trains customers are being told they can use their tickets on Chiltern Railways, CrossCountry, East Midlands, LNER, Southern, Thameslink and ScotRail services to complete journeys.
A tweet from National Rail said: "A fault with the signalling system near Queens Park means that London Northwestern Railway and Virgin Trains services are currently unable to run to and from London Euston. As a result, trains may be cancelled or revised."
