Trains across Tayside and Fife have been delayed due to a signalling fault on the line.
Services between Edinburgh and Dundee have been suspended due to the fault between Dalgety Bay and Burntisland.
Trains to Arbroath, Perth and Fife are facing delays and alterations.
ScotRail have said that services are now “returning to run as scheduled” however some disruption is ongoing “because of units and crews out of position”.
The disruption is expected to last until 6pm.