Emergency services have managed to contain a fuel spill after a coal train "clipped" a large boulder near Lithgow this morning.
Fire and Rescue New South Wales said a locomotive's fuel tank was punctured after it hit the obstruction, which had fallen on the tracks near Portland.
Superintendent Adam Dewberry said the two-metre-wide boulder had likely been dislodged by recent heavy rainfall.
"It just clipped the boulder and punctured one of the fuel tanks," he said.
The fuel tank, loaded with 9,000 litres of diesel, was losing about one litre a minute.
Superintendent Adam Dewberry said matters were under control and that leakage during the four hour operation was "minimal".
Personnel were decanting the diesel into steel drum before a fuel tanker arrived on the scene.
"Fortunately it was only a minor leak, but still enough to cause trouble," Superintendent Adam Dewberry said.
The incident occurred at about 8:30am this morning.
Fire and Rescue HAZMAT crews were on the scene working to avoid impacts on waterways.
The NSW Environment Protection Authority has been contacted for comment.
