The choice of a former mining industry consultant to head a government investigation into AGL's discovery of toxic chemicals at its coal-seam gas operations raises doubts about the probe's impartiality, a local opposition group says.

Lee Shearer, an ex-NSW policewoman from the Newcastle region, is overseeing the Department of Resources and Energy's probe of the AGL's coal-seam gas operations near Gloucester. The company was ordered to suspend its pilot project last month after revealing it had detected banned BTEX chemicals in its flowback water after fracking.

Mining ties queried: Anti-CSG protesters in Gloucester last October. Credit:Dean Sewell/Oculi

Energy Minister Anthony Roberts praised Ms Shearer, now in charge of his department's compliance and enforcement unit. "As former senior NSW police officer, Lee Shearer is just a remarkable individual, so we take compliance very seriously," Mr Roberts told a delegation to Sydney last week from the anti-CSG group, Groundswell Gloucester.

The residents group, though, said Ms Shearer's past role as a consultant to the mining industry, including "managing crisis situations" fanned worries about her independence.