Broken down train between Princes Risborough and Aylesbury causes cancellations
Trains running between these stations may be cancelled or delayed by up to 60 minutes.
The broken down train is also causing congestion between Princes Risborough and High Wycombe, where trains may be cancelled or delayed.
Disruption is expected until 18:00.
Network rail are willing to compensate anybody affected by the cancellations.
"You may be entitled to compensation if you experience a delay in completing your journey today.
"Please keep your train ticket and make a note of your journey, as both will be required to support any claim."