East Taieri businessman Andrew Simms said another Dunedin City Council workshop next week would do nothing to further public confidence in the process.
Public feedback to the council about its proposal was strongly against a sale.
"There is increasing concern amongst the community that those bureaucrats promoting the sale of Aurora are controlling the agenda and have twice been granted, without a motion of council, extra time to try and convince sufficient numbers of councillors to sell Aurora.
"The ever-evolving process around the proposed sale of Aurora has lacked credibility from the outset and continues to be manipulated by those intent on selling the asset."
The city council denied the process had been tilted towards a decision to sell.
"We categorically reject any suggestion we’re manipulating the process around the Aurora Energy proposal," a council spokesman said.
Aurora is part of the council’s Dunedin City Holdings Ltd (DCHL) group and in May DCHL requested more time to present information.
The council spokesman said councillors agreed to this and a workshop was held on July 1.
The workshop scheduled for Monday would allow councillors to "ask questions of staff, highlight any issues ... and consider modelling on a range of financial scenarios".
It is expected to be closed to the public and council chief executive Sandy Graham said information could be made available afterwards.
"All of this does mean the timeframe for a decision has been extended, but that is immaterial compared to the significance of the decision to be made by councillors," the council spokesman said.
Mr Simms is the Mosgiel-Taieri Community Board chairman, but has been commenting about Aurora in his personal capacity.
"Given the very high level of public and media interest, and given that much of the information previously presented by DCHL and its advisers has not stood up to public scrutiny, the decision to hold this latest workshop non-public is highly concerning."
He did not accept commercial sensitivity made it necessary for Monday’s workshop to be held behind closed doors.
An expected sale price above $1billion had already been "bandied about" and modelling would merely look at hypothetical scenarios.
A public hearing was held in May and "it was apparent that many councillors had likely been swayed towards retaining Aurora".
DCHL then spent tens of thousands of dollars to receive content from consultants and to book flights for people making presentations at last month’s workshop.
The council initially signalled a decision about selling or retaining Aurora could be made in late June or early July, but it has now indicated a decision could be made next month.
Dunedin Mayor Jules Radich said he was comfortable with the time being taken to assemble information.
