Crown agency Callaghan Innovation has been given a clean bill of health over its handling of Official Information Act requests following complaints it had "stonewalled" the Taxpayers' Union.
Chief Ombudsman Peter Boshier released a statement this afternoon, saying he had found no "wrong, unreasonable or contrary to law" conduct by the agency.
But the Taxpayers' Union has hit back, saying Mr Boshier's investigation "totally ignored" the relevant time frame and came close to turning a blind eye.
Mr Boshier said he took the allegation "extremely seriously". His investigative team interviewed everyone involved and "carefully examined" how long the agency took to respond to Official Information Act (OIA) requests, he said.
"I found the Taxpayers' Union's concerns were not borne out by my review of Callaghan's actions," Mr Boshier said.
"A generally positive culture exists around the importance of the OIA, and organisational transparency."
The investigation's final report made no formal recommendations, but did note the need for "more targeted training for staff and improvements to recordkeeping".
Taxpayers' Union executive director Jordan Williams questioned the Chief Ombudsman's conclusions and the inquiry's time frame.
He said his complaints had centred on Callaghan's actions through 2016 and early 2017, but the investigation appeared to cover only late 2017 and 2018.
"We had an internal whistle blower at Callaghan Innovation approach us alleging that our requests under the OIA were being treated differently", Mr Williams said.
"The reports from the whistle-blower led us to file requests under pseudonyms. When we used pseudonyms in 2017 and 2018 we didn't have the same troubles getting requested information."
In a statement in response, Mr Boshier said his investigation reviewed statistical data dating back to the beginning of 2016.
"We also talked to the person referred to by the Taxpayers Union and their information was taken into account."
Mr Boshier said he remained concerned by the use of pseudonyms when asking for public information.
"Even though it is not unlawful, I still think it is a shame that requesters feel they need resort to fictitious names when requesting information."
Callaghan general manager market and sectors Erica Lloyd said she welcomed the inquiry's findings.
"The Ombudsman's review was constructive and includes helpful suggestions for improvements, many of which we started implementing last year. We have a clear roadmap to continuously enhance our OIA practice."