Delays are likely on the main train line between Inverness and Aviemore due to a signalling problem.
ScotRail is advising passengers the disruption is expected to last until 10am.
Train services between Inverness and Edinburgh will be delayed or revised.
Inverness train line signalling problem
Services to Glasgow Queen Street are also impacted by the fault.
Trains are currently running more than three hours late with fewer carriages.
A message on the Scotrail website said: “We have received reports of a signal fault between Kingussie and Aviemore affecting services towards Inverness.
“Our staff are en route and will be on site shortly.”
Signalling problem on Inverness to Aviemore train line leads to delays