The Chief Ombudsman has published an opinion on the Department of Corrections' decision to withhold information from the business case on Wiri Prison.

The complainant had sought completed and unredacted versions of the first and second business cases for the prison.

After the department provided information which redacted all mentions of the capital cost of the proposed new prison, a complaint was lodged with the Ombudsman. The complainant said he wanted the information specifically so he could compare the cost of Public Private Partnership procurement with other forms of building a new prison.

Judge Peter Boshier says he accepts that release of the information would prejudice or disadvantage the department in negotiating a favourable outcome for future prison projects.

He says he was not persuaded that the public interest in terms of section 9(1) of the Official Information Act 1982 in making available the information at issue outweighed the department's protected interest under section 9(2)(j).

"In fact, it is in the public interest that the department's negotiating ability in regard to future prison projects is not undermined," he concludes.