The incident occurred shortly before 6am near Geurie and involved a freight train travelling from Orange towards Dubbo and came after flooding from overnight storms caused damage to the track, Transport for NSW confirmed.

There were no reported injuries to the crew of the train and no dangerous goods on board, a Transport for NSW spokesperson said.

Further investigations are under way, and buses are replacing passenger train services between Wellington and Dubbo.

"Information is still being gathered, but at this stage we can advise that a freight train travelling from Orange towards Dubbo has derailed near Geurie, following damage to the track caused by flooding due to storms overnight," the spokesperson said.

"This railway line is operated and managed by John Holland Rail on behalf of Transport for NSW.

"The railway line is currently closed to all services, while investigations, train recovery and track repair works are underway.

"Passenger services are being bussed between Wellington and Dubbo.

"The line will reopen once track repairs are complete and the track is certified as safe.

"At this stage, there is no confirmed date for the reopening of the line."

The spokesperson reports John Holland is undertaking further investigations in accordance with its obligations as the rail infrastructure manager.

The Bureau of Meteorology recorded 63.6mm of rain falling in the 24 hours to 9am on Saturday at its Dubbo airport station.