A fault with the signalling system is causing delays for passengers travelling north from Aberdeen.
The issue was discovered between Forres and Elgin, and is affecting services between Aberdeen and Inverness / Inverurie.
Train passengers are able to use their tickets on Stagecoach buses in the meantime.
A statement on ScotRail’s website says: “Our engineers are on site working to rectify the fault and require a bit more time. Once we get an update from our staff on the ground we will pass this information on.
It continues: “Customers with valid Scotrail tickets can travel on Stagecoach North bus services between Inverness and Aberdeen, with the exception of Dyce and Insch in both directions. Please present your ticket to the bus driver on joining bus services.
“Customers with valid Scotrail tickets can travel on local bus services between Dyce and Aberdeen in both directions where bus services are operated by First Bus.”