The former diplomat who was drawn into a "flawed" Government inquiry says compensating him for his losses and the damage caused will not be cheap.

Former High Commissioner to the United Kingdom Derek Leask said he had been "vindicated" today after a four-year fight with the State Services Commission to clear his name.

A report released this morning by Ombudsman Ron Paterson said that the Dame Paula Rebstock-led inquiry into the leaking of documents at the Ministry of Foreign Affairs and Trade (MFAT) in 2012 was "flawed" in its dealings with Mr Leask.

Mr Paterson recommended that the commission make a public apology to him, reimburse his costs, and compensate him for the damage done to his reputation.


Speaking to the Herald today, Mr Leask would not reveal his legal costs or say what he was seeking in compensation.

But he noted that he had needed extensive legal advice during the drawn-out battle with the commission.

"In the face of what I regarded as very high-level and aggressive onslaught, I have had to employ good counsel for four years, and I've had a QC for a large chunk of that period.

"That means that this was not a cheap exercise."

Mr Leask said he wanted State Services Commissioner Iain Rennie to step aside from any decisions about potential redress, saying that he had a conflict of interest.

"I am deeply disappointed that under their stewardship an investigation of such fundamental importance was conducted in a way which was multiply flawed, from start to finish," he said.

"The public service has to weigh [Mr Rennie's] interests against mine. You cannot ask him to be the scales on this. He has to step aside from that."

Mr Rennie apologised to Mr Leask today for wrongly implying in a radio interview in 2013 that the experienced diplomat had leaked sensitive documents.

But the commissioner stopped short of a public apology, saying that his department was still discussing potential forms of redress with Mr Leask.

Mr Leask said he also "resented" comments by Foreign Affairs Minister Murray McCully at the time.

"Mr McCully can apologise if he wishes," Mr Leask said today.

Mr McCully, while not naming Mr Leask, said in 2013 that MFAT staff at the heart of the case had been "unprofessional" and "disreputable".

He stood by his comments today.

"The Ombudsman's review criticises the steps taken in assessing the responsibility of particular individuals for some very unprofessional behaviour, but does not dispute the fact that those behaviours occurred," he said.

"My statement, made at the time of the release of the Rebstock report, referred to 'unprofessional and disreputable' conduct, but did not name any individuals. My statement was undoubtedly correct."

Mr Leask said the Rebstock inquiry had made it near-impossible for him to work in any Government-related role after leaving MFAT.

"I've never regarded this as a sob story. But obviously I don't like being defamed and that has had its personal implications.

"Obviously I don't like pitting my overdraft against the bottomless pocket of the State Services Commission.

"My family is very conscious of the fact that for the last four years, instead of being gainfully employed ... I have had to deal with this investigation."

Prime Minister John Key said this afternoon that he had confidence in Mr Rennie and Dame Paula.

Mr Key said Rennie - who is stepping down as commissioner - had made some errors but had not committed a sacking offence.

Dame Paula is a high-profile consultant who has been used regularly by the Government as a troubleshooter.

Mr Key said the Government would continue to employ her in future.

"She's made one mistake but she's done a lot of work for the Government over a very, very long period of time.

"I think on balance we'd say clearly people need to take some learnings from it but I don't think that's terminal in terms of her capacity to do work with the Government."