Urgent tests are being carried out on air, water and soil near the QLD town of Hopeland, amid fears an underground fire may be producing noxious gases.
Gases have been detected in soil on private properties near the Western Downs community.
Environment department director general Jon Black says extra resources have been sent to the area to determine the cause of the contamination.
"At this stage we cannot rule out an underground fire as the cause of these gases being present in the soil," he said in a statement issued on Tuesday.
So far Queensland Health has not identified any health risk, with more test results due later this week.
"While there is no evidence at this stage to suggest any risk to local drinking water supplies, rivers and ground water, including stock and domestic bores, the department is committed to conducting a thorough investigation and has initiated further testing," Mr Black said.
He said the results would be released once they'd been reviewed by health experts and scientists, and the community would be kept informed.
Landholders have been advised that because the gases are in subsoil, any immediate impacts to grazing animals are extremely unlikely.
But landholders have been told to contact the environment department before carrying out any excavation work or other activities that would penetrate the ground to a depth of two metres or more.
On Monday, an energy company denied any link between the contamination and its nearby underground coal gasification plant.
Linc Energy said its Chinchilla plant - located near the two Hopeland properties that returned positive soil tests for carbon monoxide, hydrogen and hydrogen sulfide - was no longer operational and hadn't been since 2013.
The three gases are among those produced through underground coal gasification.
The controversial practice involves igniting the coal seam, with oxygen pumped into a chamber to allow for the combustion of the coal, which then produces gas.