The Orakei councillor has urged the mayor to reconsider the process behind approval of the V8 Supercar event, which has also seen access to a risk-assessment report of the event denied to public and councillors.
"I urge you to call an urgent extraordinary meeting of the full council on your immediate return from the Pacific Islands.
"A full council meeting would enable all councillors, senior staff and the public the chance to view and assess the reports with complete transparency - something Audit NZ encouraged in its damning 2011 report into Hamilton," wrote Mr Brewer.
He goes on to pan the council's decision to create a "project oversight group", which the council last night said was to have "final sign-off".
"I urge you to drop the idea of a small working party meeting behind closed doors, and have all information presented to all councillors in the full glare of public scrutiny, apart from obviously that information which is legally and commercially sensitive."
Mr Brewer said any further progress with the V8 event would best be made with the mayor present.
"I believe Aucklanders would also be comforted if they knew the mayor was part of the discussions and decision-making."
The Auditor-General's office is investigating a complaint from Councillor Cathy Casey about the secret reports.
Dr Casey has asked if the council should have had access to the reports, and whether withholding information compromised last week's approval decision.