Legal advice about controversial councillor Benedict Ong's behaviour has cost the Dunedin City Council almost $10,000.

That is on top of investigation costs involving the councillor, which exceed $17,000.

The costs were included in information released to the Otago Daily Times after a request under the Local Government Official Information and Meetings Act.

Also released were parts of a report by independent investigator Steph Dyhrberg about Cr Ong allegedly breaching the council's code of conduct by sharing confidential information.

The council accepted the findings of her report and agreed he had breached the code.

It suspended him from all council committees and subcommittees for nine months, ending February 18 next year.

In her report, Ms Dyhrberg said Cr Ong disclosed information that had been clearly marked commercial in confidence and which was received in a non-public meeting.

This was a serious matter, she said.

His repeated copying in of journalists to ensuing email exchanges, also marked confidential, compounded the breach, she said.

"It appears highly likely that Cr Ong's repeated breaches of confidentiality were deliberate."

Early in the term as a new councillor, Cr Ong complained about fellow councillor John Chambers, but his complaint was found to be without substance.

Cr Ong was then himself at the centre of a complaint, after he attacked a staff member in an email.

He was found to have breached the code.

The next complaint came after he disclosed confidential information about a proposed hotel development beside Dunedin's Forsyth Barr Stadium and other content about council company Dunedin Venues Management.

Content from Ms Dyhrberg's final report about this was released to the ODT today.

Cr Ong's conduct had potentially compromised the interests of the council and its subsidiary, she said.

"That makes it a particularly serious breach.

"Cr Ong seems to have conflated public accountability or transparency of elected officials with public disclosure. That is a false equivalence."

The council met in May and agreed on the suspension for Cr Ong.

He can continue to attend full council meetings.

Information released to the ODT included an extract from the confidential minutes of the May 18 meeting.

At 1.33pm, Cr Ong "stood from his seat, declared himself as not able to be in the confidential meeting and declared himself as barred from attending confidential meetings and left the meeting", the minutes said.

At 1.41pm, city services general manager Scott MacLean invited Cr Ong to return to the meeting and advised him he could have his say.

Cr Ong refused the request.

A further complaint has since been received about Cr Ong's conduct.

It was filed by deputy mayor Cherry Lucas, alleging Cr Ong had again publicly posted confidential information and criticised the council's chief executive on social media.

An investigation into that is continuing.