Caretaker conventions place strict limits on what public officials can say in an election campaign, but Fairfax Media understands the NBN Board decided it was necessary to intervene given the high-profile raids last week. NBN chairman Ziggy Switkowski has defended the referral to the AFP. Credit:Luis Ascui Australian Federal Police officers last week raided the Melbourne office of former communications minister Stephen Conroy and the home of a Labor staffer as part of an investigation into the alleged leaking of confidential NBN documents. Opposition Leader Bill Shorten accused the Turnbull government - through the NBN - of muzzling whistleblowers and limiting the public's right to know about the progress of one of the biggest infrastructure projects in Australian history. "When dozens of confidential company documents are stolen, this is theft," Dr Switkowski writes in an opinion piece, published by Fairfax Media.

"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." Then communications minister Malcolm Turnbull appointed Dr Switkowski, the former chief executive of Telstra, to chair the NBN in 2013. He has overseen the transition from a full fire-to-the-premises rollout to a mixed technology model including use of existing copper networks. "One rationalisation has appeared that this theft is the action of whistleblowers," he writes. "No, it is not.

They cannot give voice to their preferred ideology by passing on stolen documents "NBN has a well established process for responding to information from whistleblowers with a notification process managed by an independent third party . None of the matters in the stolen documents have been raised through this channel. "If an employee has strong personal conviction unsupportive of a company's strategy, they can argue their case with management or resign. "They cannot give voice to their preferred ideology by passing on stolen documents." The warrant issued by the AFP said police were seeking documents relating to The Sydney Morning Herald, The Australian Financial Review, The Australian, the ABC and technology website Delimiter.

These outlets have published a series of damaging stories, based on internal NBN documents marked "commercial in confidence", about the the poor state of the cable TV and broadband network it purchased from Optus and of the copper network purchased from Telstra. "Contrary to media commentary, the documents did nothing to highlight poor management of the business," Dr Switkowski writes. "There are no 'cost blowouts' or 'rollout delays' to the publicly released plans - all one has to do is compare the data that is readily available. "The documents show progress updates, options to ensure targets are met and ways to solve problems which are all normal parts of doing good business. "It's simply wrong to diminish NBN's performance, because such accusations are not supported in fact."