Disruption to rail services due to cracks in trains is expected to continue for weeks.
Hitachi Class 800 trains used by GWR and London North Eastern Railway (LNER) were withdrawn from service on 8 May after safety checks found cracks in part of the chassis.LNER is currently running a reduced service on the East Coast Main Line while GWR advised passengers with tickets for long-distance journeys on 10 May not to travel.
This was due to "no service or an extremely limited service" between London Paddington and Bristol Temple Meads, Penzance and Cheltenham Spa.
The Department for Transport has called on the rail industry to "urgently set out a comprehensive plan" to resolve the disruption.
Chris Heaton-Harris, Rail Minister, has asked Hitachi to identity the extent of the cracking and whether "can still run safely".
A spokesperson for Hitachi said the cracks are on lifting points under train carriages, which are used during maintenance.
Hitachi also thanks all passengers for their ongoing patience.