Martin Parkinson, the head of the Department of Prime Minister and Cabinet (DPMC), has rebuked the chief of the NBN.

National Broadband Network CEO Ziggy Switkowski has written an opinion piece for Fairfax Media detailing his view on police raids on the offices of a Labor Senator in May.

He appears to have been prompted to write the piece after criticism that the government-owned entity had become ‘politicised’ by handing over information that led to raids on an Opposition MP.

“Misinformation about NBN and accusations of underperformance are inexcusable and galling,” Dr Switkowski wrote in the article.

“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 process is a form of political 'rumourtrage' - the circulation of misinformation to diminish an enterprise for political gain.”

Australia’s top public servant Martin Parkinson has now written a response.

He says Dr Switkowski may have breached caretaker convention by publishing the article during the election cycle.

“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,” Dr Parkinson said.

“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.”

NBN has issued a statement defending Dr Switkowski's opinion piece, which it claims “addressed misleading claims to restore the trust of its 5,000 employees”.

“Inaccurate comments that accuse the company of deliberately misleading, deliberately concealing, and then persecuting innocent whistle-blowers have a tremendously corrosive effect on morale and jeopardise the great gains made over the last few years,” the statement said.

“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 Dr Parkinson notes that while the caretaker conventions do not carry any “legal force”, maintain the apolitical and impartial nature of the public service “is a matter of the highest priority”.