High speed rail services have been cancelled or delayed across large parts of England after cracks were found on some trains.
Passengers were warned that the delays and cancellations could last into the working week and that people should not try to travel on Sunday.
At least four rail companies endured delays and cancellations after the cracks were found and trains taken out of service for inspection.
London North Eastern Railway, Hull Trains, the TransPennine Express, and Great Western Railway, all have trains being inspected as a "precaution".
All 93 of GWR's Hitachi 800 trains are offline meaning major delays between London and Penzance and Cardiff. Problems at the other companies saw the ripple effect hit Birmingham and Manchester.
Railway minister Chris Heaton-Harris warned disruption was likely for a "prolonged period".
"Trains will be returned to service as quickly as possible once they are fully approved as safe by the manufacturer," Mr Heaton-Harris said.
"I share the frustration of passengers who are experiencing significant disruption, and would ask people whose journeys are affected to check before travelling."
He also warned that GWR was expected to see the most serious disruption.
GWR advised people to check before travelling on Sunday and added the disruption was "expected to continue into the following week".
Hitachi said inspections on trains were continuing and that some trains had been put back into service.
"Safety is our number one priority and as a precaution, the decision was taken to halt the entry into service of our intercity fleets pending inspection," Hitachi said.
"We understand the frustration caused and we would like to apologise for the inconvenience caused to passengers and operators."
Hull Trains said services would resume after "thorough checks by Hitachi" on its fleet.
