Rail services on Great Western Railway (GWR) and London North Eastern Railway (LNER) are being disrupted for a third day due to cracks in trains.

GWR advised passengers with tickets for long-distance journeys on Monday “not to travel” as there is “no service or an extremely limited service” between London Paddington and Bristol Temple Meads, Swansea, Penzance, Hereford and Cheltenham Spa.

LNER is running a reduced service on the East Coast Main Line, which runs between London King’s Cross and Edinburgh via Peterborough, York and Newcastle.

The operators’ Hitachi Class 800 trains were withdrawn from service on Saturday for safety checks after cracks were discovered in part of the chassis of some trains.

Robert Nisbet, director of nations and regions at industry body the Rail Delivery Group, said if inspected trains are found to have “tiny cracks” then replacement trains may be deployed while repairs are carried out.

Asked if he knows how long the disruption is likely to last, he told BBC Radio 4’s Today programme: “No, I can’t put an exact time on it and that is purely because we are going through the process and taking it extremely seriously.”

Mr Nisbet described the disruption as “disappointing” because more passengers are returning to using the train network following the easing of coronavirus restrictions.

In response to a question on how long trains have been running with cracks, he said: “These trains are relatively new in service, so this is something that the Hitachi engineers will be looking at and reporting back to the train operating companies.”

On Sunday he said that the cracks – measuring millimetres – are on the “lifting points on the underside of the carriages used for maintenance”.

He added that this “didn’t pose any particular danger to passengers” but they “have the potential to develop” if left untreated.

The Government called on the rail industry to “urgently set out a comprehensive plan” to resolve the disruption.

Rail minister Chris Heaton-Harris asked Hitachi – which builds and maintains the Class 800 trains – to identify to extent of the cracking and “whether carriages can still run safely” despite the issue, the Department for Transport said.

He also also urged the industry to manage capacity by using “alternative trains” on the affected routes, and delivering a “clear rail replacement schedule” using buses and coaches.

Hitachi apologised to passengers and train companies, adding that some trains have returned to service after being checked.

In addition to the revised train service arrangements GWR ticket holders may utilise the following local bus routes should they assist with individual journeys -

Route 10 Gloucester - Cheltenham

Route 23 Gloucester - Lydney

Route 61 Stroud - Stonehouse

Route 63 Gloucester - Stroud

Route 64 Gloucester - Stonehouse - Stroud

Route 65 Stroud - Cam & Dursley

Route 66 Cheltenham - Stroud - Stonehouse

Route 71 Gloucester - Tewkesbury

Routes 97 / 98 Gloucester - Cheltenham

Routes 94 & 94X Gloucester - Cheltenham