City council won't release a draft audit from 2006 into the construction of a major government building in downtown Windsor for fear doing so would be illegal.

Councillors on the city's audit committee decided on Wednesday that they couldn't release the document after receiving legal advice from Andrew Roman, of the Toronto firm Miller Thomson LLP, who told the committee that the report's release would violate Ontario's Municipal Act.

The report's release could also lead to lawsuits because the report contains assumptions and inaccurate legal positions, Roman said.

Audit committee member Coun. Alan Halberstadt supports the decision, saying he would prefer to release the report but that ultimately "secrecy is required."

"To release it would be at our peril and my peril because it's illegal," he said.

The draft audit, prepared by former city auditor Mike Dunbar was the first step in a three-year review of the construction of the building at 400 City Hall Square Hall.

Construction on the building began in 2003, with a projected cost of $23 million. With council-approved additions and changes, the final cost of the project was $32 million.

The original draft audit was submitted to the city's chief administrative officer in December 2006. Dunbar resigned in December 2007.

In April 2008, then-CAO John Skorobohacz announced that new financial information and construction issues had emerged, and that they would need to be investigated before a final report could be released.

The first part of that final report, released on Feb. 17, made 19 recommendations to improve transparency, accountability and control in future building projects.