BHP Billiton has closed its main iron-ore rail line linking its West Australian mines to Port Hedland because of an incident on the line.
"The affected part of our main line rail from Newman to Port Hedland has been closed and all rail construction work has been suspended until further notice," the company said in a statement today.
Separately, police said they were investigating a possible suicide of a man who was alleged to have stepped out of his vehicle to stand in front of an oncoming train around 4am local time.
A spokeswoman for Western Australia police said speculation the man drove his vehicle onto the track was incorrect.
BHP said it would provide further details later after meeting with police investigators.
A typical BHP ore train is about a mile long and consists of 300 cars hauling 24,000 tonnes of ore each hundreds of miles to waiting freighters.
On average a trainload leaves a mine every hour day and night.
BHP, the world's No.3 iron ore miner, ships all its ore via Port Hedland and each month accounts for the majority of the roughly 15 million tonnes entering the port.
Rio Tinto, the world's No.2 iron ore miner, use separate lines and does not ship ore to Port Hedland.
Reuters