Trains services between Nottinghamshire and Derbyshire have been disrupted after a signalling fault at Radford Junction.
This is causing problems to East Midland Trains services on the Nottingham to Mansfield Woodhouse route and Liverpool Lime Street/Nottingham/Norwich route.
On the Nottingham/Mansfield/Worksop route no trains are running in either direction.
On the Liverpool Lime Street/Nottingham/Norwich route, trains will be diverted via Derby where possible but will be unable to call at Ilkeston, Langley Mill or Alfreton.
Replacement bus services are being arranged from Nottinghamshire to Derbyshire.
A spokesman for East Midlands Trains said: “At present Network Rail is investigating the problem. The team is working to understand how long repairs to the signalling will take.
“At this early stage we do not have an estimate as to when the line will fully. We will keep you updated when we have more information.
“We are arranging for rail replacement buses to run in place of trains between Nottingham and Mansfield Woodhouse and also between Nottingham and Chesterfield for customers travelling to/from Ilkeston, Langley Mill or Alfreton.
“You may also use your rail ticket on board NET Trams between Nottingham and Hucknall.
“We are sorry for the delay to your journey today.”