Rail passengers are facing major disruption because of a signalling problem between Euston and Watford Junction.

Network Rail said a fault with the signalling system between the two stations had caused some lines to be blocked, potentially causing some services to be severely delayed or cancelled.

In an update on Saturday evening, the publicly-owned organisation responsible for the rail tracks said it expected the disruption to continue “until the end of the day”.

The signalling issues meant trains running on the major rail section “may be cancelled, delayed by up to 90 minutes or revised”, Network Rail said in a social media post.

Avanti West Coast, the train operator that runs services to Manchester, Liverpool and Glasgow, said it was putting on rail replacement coaches to take passengers from Euston to Watford and Milton Keynes to bypass the problem.

Other operators affected included London Overground, Southern, London Northwestern Railway and Lumo.

London Northwestern Railway said the trouble specifically related to a signalling issue in the “Camden area”.

Passengers took to social media to express their frustration, and warn others heading to Euston about the likely delays to their journey.

Nicola Ruth tweeted a picture of Euston’s crowded station concourse and said: “Here's my real life Halloween horror – all lines blocked leaving Euston this evening.”

Akira Murakami, an associate professor at the University of Birmingham, posted on X: “Due to a traffic light malfunction, all trains departing from London's Euston Station are delayed.

“It seems like after the delay announcements, they're being canceled one by one, so it might be a good idea to look for another way to get home.”

Shamim Chowdhury, a foreign correspondent, tweeted just before 6pm: “Massive signal failure between Camden & Euston station. No trains arriving at Euston.

“Backlog of trains stretching north beyond Milton Keynes. We're sitting here with no idea about when we'll get home. Many frustrated passengers. Total chaos.”

The issues created disruption for those on the Tube as well, with Euston Underground closed by Transport for London as a result of overcrowding at the station.

One Tube passenger told The Standard they were told by the driver of their Northern line train that they would not stop at Euston because of problems being experienced with intercity services.

Many passengers impacted by the signalling failure looked for alternative routes to travel to their destination.

That caused Marylebone station, and services leaving from the central London terminal, to be very busy, according to Network Rail.

In an update issued at 8.30pm, Network Rail said some trains were able to pass through the affected stretch of track into Euston.