Dr Parkinson wrote that the investigation concluded some elements of the May 28 article "are not consistent with established practices around caretaker conventions which are directed at protecting the apolitical nature of government bodies and preventing controversies about the role of those bodies distracting attention from the substantive issues in the election campaign". National Broadband Network chair Ziggy Switkowski. Credit:Chris Hyde "I have conveyed this view directly to Dr Switkowski," he wrote in his letter to Mr Burke. But the more damaging revelation is that Dr Switkowski was "strongly" warned against submitting his article for publication because it would breach the requirement on public servants to avoid being seen to participate in public discussion and to remain above the fray during an election campaign. "I understand from my inquiries that NBN provided an advance draft of the article to the Department of Communications and the Arts," Dr Parkinson advised Mr Burke.

"The Department of Communications and the Arts sought, and received, advice from the Department of the Prime Minister and Cabinet that the publication of the article in that form was not consistent with the established practices associated with the caretaker conventions. I understand that view was strongly conveyed to NBN by the Department of Communications and the Arts, as was the view that the conventions apply to the chairman, as well as to the CEO and the company. Our understanding is that this view was passed to Dr Switkowski." Australia's top public servant, Dr Martin Parkinson, delivered a speech at the National Portrait Gallery on Tuesday. Credit:Alex Ellinghausen Even Malcolm Turnbull's Cabinet Secretary Arthur Sinodinos said Dr Switkowski's decision to weigh in publicly was debatable: "I don't think he did anything wrong, but I think he should have realised he was probably walking into a political minefield". The furore was sparked after the Australian Federal Police raided the office of Victorian Labor senator Stephen Conroy and the home of an opposition staffer during the first week of the campaign. The raids, which touched off a major public debate about the government's role and knowledge in the raids and the AFP's particular behaviour in choosing the heat of an election campaign to conduct such unusual and high-profile actions, revealed the extreme sensitivity of both the government and the NBN management to criticism over the $50 billion-plus project.

They had followed a series of stories published by Fairfax Media in late 2015 and early 2016 revealing leaked confidential internal reports exposing blow-outs in time and cost within the giant operation. Letter from Martin Parkinson In his opinion piece, Dr Switkowski branded what Labor and others had cast as "whistle-blowing" by concerned NBN employees as theft. "If an employee has strong personal conviction unsupportive of a company's strategy, they can argue their case with management or resign," he wrote. "They cannot give voice to their preferred ideology by passing on stolen documents."

"When dozens of confidential company documents are stolen, this is theft. "When they are the basis of media headlines and partisan attacks, they wrongly tarnish our reputation, demoralise our work force, distract the executive, and raise doubts where there is little basis for concern." The NBN has become one of the flashpoints of the 2016 election. Labor released its NBN policy in recent days, promising to discontinue the hybrid-technology use of copper phone lines for the final loop to the premises, ordered by Malcolm Turnbull when he was communications minister, and complete the job using optical fibre where possible. But the government attacked Labor's claim that this could be done within the $57 billion envelope and the same time frame. The AFP is continuing to investigate the leaks, despite the fact that the documents seized from the opposition have been sealed after Senator Conroy claimed they were the subject of parliamentary privilege. The status of the documents will be determined by the Senate after the election.

Dr Parkinson concluded his letter to Mr Burke with the assurance that he takes the impartiality of the public service "as a matter of the highest priority". NBN Co spokeswoman Karina Keiser defended the opinion piece. "Any accusation that the company's staff, management, its board and (by implication) its shareholder departments, have conspired to keep large cost increases secret from the Australian people is not only plainly and demonstrably false, but is a serious accusation in light of the Corporations act (for example section 184)," she said. "This is obviously not acceptable and the opinion piece addressed the allegations in a manner commensurate with the mode in which they were made; that is, publicly in the national media." But Opposition Leader Bill Shorten branded Dr Switkowski's performance shameful. "I think for an otherwise respected businessman, Dr Switkowski, I think this is a shameful breach," he said. "Yet again NBN Co are doubling down on the cover-up, the denial." Loading