A train came off the tracks close to Stonehaven. It is believed nobody was injured in the incident and the train was not carrying any passengers.
Scotrail told rail travellers services between Edinburgh and Aberdeen will be cancelled or terminated at Dundee.
Replacement buses between Aberdeen and Dundee are currently being organised by Scotrail, but delays are likely.
A statement on the ScotRail website said: “A train has become derailed at Stonehaven which is preventing us from running any trains through this area.
“We expect that disruption will continue until the end of service.
“We’re organising replacement buses to operate between Aberdeen and Dundee but these have not yet been confirmed. Please check back here for updates.
“If you’re travelling to Aberdeen you can use ScotRail services via Inverness. This will add significant time to your journey. Check before you travel to ensure you’ll be able to make a connecting train at Inverness.”
Routes from Glasgow are also affected.