"Can the mayor impose such restrictions of me? Can he really withhold in part a report paid for by ratepayers' money?" Casey asked the Ombudsman.
Casey said today she awaited the Ombudsman's response with interest.
Boshier said the first stage of his investigation had now started.
"I have written to the chief executive of Auckland Council and notified the complainants.
"I am unable to comment any further as I am required by law to treat all evidence as confidential and all inquiries secret.
"However, I do wish to complete my investigation as soon as possible given the high public interest in this case."
In a statement, Goff welcomed the decision of the Chief Ombudsman to investigate the provision of the PWC Stadium Report to councillors.
"Full and unredacted copies of the report have from the beginning been available to all councillors.
"I am keen to be transparent in the provision of the information to councillors. Equally, I have an obligation to ensure the confidentiality of commercially sensitive information belonging to third parties.
"My office and council staff will co-operate fully with any requests from the Ombudsman," Goff said.
The mayor has been under fire after councillors' access to the stadium report was restricted.
Nearly half of Auckland councillors this week penned a letter of no confidence in Goff after his refusal to give councillors full and open access to a $923,000 report by PwC on a proposed downtown stadium.
Goff has said he was maintaining confidentiality by not giving councillors full and open access to the reports.
The pre-feasibility report by PwC found a stadium with a capacity of 55,000 spectators for rugby, league and football and 65,000 for concerts could be built in the central city for between $1.1 billion and $1.5b.
In a response to the letter from nine of the 19 councillors yesterday, Goff said he had "made copies of the full reports immediately available to councillors to read".
"To honour obligations to those who required confidentiality, the report was not circulated in an electronic form. In response to requests from councillors, I was happy subsequently for councillors to hold and to read the report in their offices," he said.
In the letter Goff said council staff had advised him "that the Ombudsman is satisfied with this arrangement and regards it as acceptable".
Council governance director Phil Wilson said the council would co-operate fully with the Ombudsman's investigation.
"The full, unredacted reports had been made available to Councillors to view in the Office of the Mayor. However, following concerns raised by councillors about this arrangement, and further discussion with the Ombudsman, council took steps to address the concerns by making full, unredacted copies available to them upon request.
"In making the decision to release the information in this way, we understood we were addressing the councillors' concerns.
"We intend to address any wider concerns by developing a protocol around information to be agreed by the elected members themselves and will progress this as quickly as possible," Wilson said.
"We have received advice that the Ombudsman wishes to look further into this matter and will of course co-operate fully. This follows an earlier complaint from three Councillors about access to two reports on future stadium needs and options in Auckland.
"The full, unredacted reports had been made available to Councillors to view in the Office of the Mayor. However, following concerns raised by councillors about this arrangement, and further discussion with the Ombudsman, council took steps to address the concerns by making full, unredacted copies available to them upon request.
"In making the decision to release the information in this way, we understood we were addressing the councillors' concerns.
"We intend to address any wider concerns by developing a protocol around information to be agreed by the elected members themselves and will progress this as quickly as possible."
The Herald is seeking comment from the mayor.
