The issue is believed to be connected to cracks in the suspension of some Class 800 trains – including LNER’s Azuma trains and TransPennine Express’s Nova 1 trains.

In a message on twitter, LNER said today: "Due to a problem under investigation, services route-wide are subject to delays and cancellations. Please DO NOT TRAVEL, tickets will be valid up to and including Sunday May 16 2021 (a new reservation MUST be made)."

A spokesperson for LNER was unable to confirm this morning when replacement bus services for passengers travelling from York would be available.

But by lunctime a noticeboard on the main concourse at York railway station was advising that passengers for 'Darlington, Durham, Newcastle and beyond' could use a replacement bus service leaving from the front of the station every hour.

The company's Twitter feed said: "Coaches are en route to #Edinburgh, #Newcastle and #York. These should only be used for essential journeys."

The delays and cancellations affect trains on two of the busiest routes in the country – the East Coast Main Line between London and Scotland, passing through York, and the Great Western Main Line to and from London Paddington.

Some trains operated by TransPennine Express and Hull Trains are also affected.

It is unclear at this stage how long the disruption will last.

GWR, which runs trains on the Great Western Main Line, has warned the problem could affect Sunday services too – though LNER has not yet made any statement about this.

Hitachi apologised for the disruption today on Twitter.

“Some Class 800s have been taken out of passenger service as a precautionary measure to allow for thorough investigations,” the company said.  “We are working with partners to resolve this issue as quickly and safely as possible. We would like to offer our sincerest apologies to passengers impacted.”

The LNER spokesman said: "This problem is being investigated by Hitachi and once trains have been checked, we hope to be able to release them back into service as soon as possible. This could affect a significant number of our services and passengers should check before they travel.”

A spokesperson for TransPennine Express added: "A number of Class 800 series trains from several train companies have been taken out of service today for checks as a precautionary measure, including our Nova 1 trains.

"This problem is being investigated by the train manufacturer and once trains have been checked, we hope to be able to release them back into service as soon as possible."

Mick Lynch, general secretary of the Rail, Maritime and Transport union, said: "RMT is fully aware of the issues that have led to the cancellation of services on LNER today and that similar problems with cracks appearing in the fleet on Great Western are also emerging.

"Hitachi needs to ensure the highest safety standards and properly investigate and rectify the issues."

We'll bring you more when we have it.

Travel alerts and updates will also be posted at bit.ly/2ISf3cG

LNER graphic showing services affected today