A number of services running between Reading and London Paddington have been cancelled and other trains are delayed.
First Great Western said a freight train has broken down at Reading West station causing 60-minute delays to some services.
Posting on Twitter this morning, First Great Western said: “Delays of around 60 minutes at Reading. Trying to shunt the broken down train now. Updates to follow.”
It is not yet known when services will return to normal.