Qld gas contamination zone widened

Gas contamination of land in Queensland's southwest may be more widespread than previously feared, with tests indicating properties outside a caution zone have been affected.

Envrionment Minister Steven Miles says preliminary results have shown elevated levels of hydrogen on three private properties outside the current 321km excavation caution zone.

The Environment Department had recently tested 70 locations - including 12 private properites - outside the zone near Linc Energy's controversial underground coal gasification plant at Hopeland, near Chinchilla.

Soil testing and drilling has been ongoing since gas contaminants were first found in February 2015.

Dr Miles said testing had continued to confirm that neither human health, water supplies, air quality or agricultural products had been impacted.

He said nobody had been banned from excavating, with landholders of properties where elevated levels of hydrogen had been confirmed were advised to take care when excavating below a depth of two metres.

"General farm work is not and never has been impacted," he said.

Legal action is underway against former Linc executives, who are facing charges of breaching environmental laws over the Hopeland operation.

The Queensland government banned underground coal gasification in April last year, the same month Linc went into voluntary administration.