The hearing was told that many farmers in northern and western NSW were angry about proposals to extract coal seam gas from their land, and some planned to join a mass campaign to lock their gates in the face of resources companies.

The NSW Farmers Association said a ''gas rush'' had been driven across NSW in the past two years because the state government had allowed a five-year exemption on paying royalties on coal seam gas extraction, to facilitate the growth of the industry.

Mr Dunn addressed a meeting - organised by the NSW Greens - in Leichhardt on Monday night. It discussed the planned drilling of an exploratory well in St Peters by a coal seam gas company, Dart Energy. He later said he stood by his comments, and that they applied to the industry in general.

''The intent of saying that is to make it clear that we have never shied away from the fact that there will be impacts on aquifers,'' Mr Dunn said.

''I'm wanting to ensure that we are not seen as saying there won't be any impacts during the process. It is a matter of monitoring and managing those impacts.''