Trains travelling in and out of Cornwall have been cancelled today after hairline cracks were found on several high-speed trains.

Great Western Railway has confirmed that a number of Class 800 series Hitachi trains had been taken out of service for checks "as a precautionary measure."

It affects all high-speed routes between London Paddington and Penzance, as well as four others.

Customers who had been planning to travel have been advised not to.

A GWR spokesperson said: “A number of Class 800 series Hitachi trains from several train companies have been taken out of service today for checks as a precautionary measure.

"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 will affect a significant number of today’s Intercity services and local lines are also likely to be extremely busy. Customers are advised not to travel.

"Refunds will be provided and customers should visit gwr.com for more information.”

The London Paddington - Reading - Taunton - Exeter St Davids - Plymouth - Penzance route is among five GWR routes affected, all connecting to London Paddington.

The company's website also gives this customer advice: "Owing to the short notice unavailability of carriages which form our High Speed train services there will be no train service or only an extremely limited service with no alternative means of transport available for throughout journeys, in either direction, on the following routes :-

"London Paddington - Swindon - Bath Spa - Bristol Temple Meads.

"London Paddington - Swindon - Bristol Parkway - Newport - Cardiff Central - Swansea.

"London Paddington - Reading - Taunton - Exeter St Davids - Plymouth - Penzance.

"London Paddington - Reading - Oxford - Evesham - Worcester - Great Malvern - Hereford.

"London Paddington - Reading - Swindon - Gloucester - Cheltenham Spa.

"Intending customers for these routes are advised not to attempt to travel.

"Avanti West Coast and West Midlands Railway are conveying passengers via any reasonable route until further notice. Arrangements have been made for Great Western Railway rail tickets to be accepted for these journeys."

Rail union RMT General Secretary Mick Lynch said the company needed to properly investigate and rectify the issues.

"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," he said. 

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

"This situation demonstrates once again that it is reckless for the rail companies and the DfT to move the industry to diluted, risk-based maintenance regimes which extends maintenance cycles on rolling stock or on the infrastructure, whether that be on the mainline railway or on the tube and metro services, to cut costs and strip out staff.  

"The railway needs to be maintained rigorously and to the highest possible standards to protect the travelling public and the staff and that will remain RMT's key demand."