Ms Gallagher announced the standing down of the steering group on August 9.

She said that the health impact assessment would continue as planned but without the steering group.

She said the steering group was set up to provide her with advice on the assessment.

''It is important to ensure that the statutory process continues in the way that it should, and because of that the governance arrangements that I originally put in place over the HIA are no longer required.

''I have given a commitment to the HIA steering group members that they can, if they so wish, feed any health information into the EIS and that I will assist in facilitating the ability for this to occur.''

Professor Capon said a health impact assessment was a more thorough way of addressing health impacts.

''Changing tack midstream, which is effectively what the Government is doing here, is not good decision making and a statutory EIS is not a better way of assessing health impacts simply because it is statutory,'' he said.

Minister for Planning Andrew Barr rejected Professor Capon's statement that the community would lose faith in the planning system.

''I have indicated following the Land Authority's preliminary assessment that [for] that particular project a full EIS was required. It supersedes all other processes and that is the planning system working.

''In fact to go any other way given the recommendations of the Planning and Land Authority would have undermined confidence in the planning system.'' Opposition Leader Zed Seselja said the community was losing confidence in the process.

''It is very significant that someone who is independent in this process who is appointed by the ACT Government has the view now that this process will not be as thorough as residents would expect and as the ACT Government would have had us believe,'' Mr Seselja said.

''These comments certainly do undermine the veracity or the thoroughness of the process going forward with the EIS.''

Residents opposed to the development would like the internationally recognised experts from the assessment to continue the report.

Canberrans for Power Station Relocation spokesman Rodahn Gibbon said the community wanted to health impact assessment finished with the steering commitee in charge.

''It is another example of the ACT Government manipulating the process to reach a pre-determined outcome,'' Mr Gibbon said.

Member for Molonglo Deb Foskey said Ms Gallagher overlooked the fact that trust was big theme of the coming ACT election when she disbanded the committee.

''Clearly, this action has lost the trust of the two expert members of this committee, whose work was well under way. It is ironical that the committee's community consultation had actually created tentative trust where there was none before,'' Dr Foskey said.

The outgoing Greens member said an environmental impact statement did not replace an health impact assessment when it came to a thorough examination of health impacts.

''The community and the Greens are wondering whether the committee was just too independent for the Government's liking.''