Calls for an independent inquiry into a £600m waste incinerator have been rejected by Gloucestershire County Council.
Campaigners claim the contract for Javelin Park in Gloucester, which is more than £100m over budget, was unlawfully awarded.
They have also launched a legal challenge in the High Court.
Last week community group R4C demanded an independent inquiry take place, claiming the multi-million contract for the Javelin Park rubbish burner was unlawfully awarded.
Replying in an open letter, the County Council's Chief Executive Peter Bungard said launching an inquiry into the independence of external auditors Grant Thornton would be too costly and over-resourced.
He added that a further inquiry cannot take place while the legal challenge now sits with the High Court.
The County Council has had three inquiries from external auditors into the contract.
Work on the project began in 2016 and the incinerator is due to begin operating in July.
The County Council have previously argued that the Javelin Park facility is good value for money, and will provide energy for 25,000 homes while saving £100million over 25 years.