The train was derailed while heading south from the small town of Boggabri in Australia's coal-rich Hunter Valley to Newcastle port.
The closed section of the railway line is part of a larger network that feeds into the port, but a prolonged outage could boost Australian coal prices, which have been under pressure in recent months due to a global oversupply of the fuel, industry sources said.
"Initial indications are that significant damage has been caused to the bridge and the track - and comprehensive repairs will be required," ARTC said in a statement.
"As a result, there is currently no forecast or estimate to returning the track to service at this stage and the line remains closed." (Reuters)