The weekly Ghan train from Adelaide to Darwin has been cancelled after a freight train derailment.
The last three freight cars of a train derailed north of Marla, in South Australia on Saturday, damaging about 400 metres of track.
Engineers and track restoration crews are working in the remote location to fix the damage.
The affected line, which mainly carries freight, could be closed for up to two days, the owner and operator of the rail line Genesee and Wyoming Australia (GWA) says.
The only passenger train service on the line, the weekly Ghan, had to be cancelled on Sunday morning, with passengers asked to reschedule their trip.
GWA managing director Greg Pauline said freight services which travel to Darwin would be delayed until the line was reopened.
"The big effect potentially is the food and essential services (that need to) get to Darwin, Alice Springs and Tennant Creek and Catherine," he said.
The cause of the derailment is not known at this stage.