The head of Australia's most secretive electronic spy agency has revealed Australia's "entire" emerging 5G mobile communications network could have been threatened if Chinese electronics giant Huawei had not been banned from supplying equipment.

Key points: Mike Burgess said the decision to block Huawei and ZTE was "not taken lightly"

Mike Burgess said the decision to block Huawei and ZTE was "not taken lightly" ASD manages risky suppliers by locking them out of providing "core" elements

ASD manages risky suppliers by locking them out of providing "core" elements Australia may need to be more vigilant about the origins of components for critical infrastructure

Australian Signals Directorate (ASD) chief Mike Burgess has told Canberra's national security community "my advice was to exclude high-risk vendors from the entirety of 5G networks" because "a potential threat anywhere in the network is a threat to the whole network".

On the last full day of Malcolm Turnbull's prime ministership and on the eve of the Liberal party room decision to elect Scott Morrison, the government quietly announced the decision to block Huawei and another Chinese firm, ZTE, providing components into the next-generation networks being built by the major telecommunications companies.

Since the August upheaval, the Morrison Government has provided little further explanation as to why these "high-risk vendors" represented an unacceptable risk to the multi-billion-dollar 5G rollout.

In a speech titled "Coming out from the shadows", Mr Burgess set out to explain ASD's role and thinking behind the ban on Chinese involvement.

The decision was "not taken lightly" and was "supported by technical advice from our agency", Mr Burgess said.

Noting that 5G technology will be at the centre of applications ranging from driverless cars to power and water supply, the computer engineer declared "the stakes could not be higher".

"This is about more than just protecting the confidentiality of our information — it is also about integrity and availability of the data and systems that we rely on in our everyday lives.

"Getting security right for critical infrastructure is paramount."

In earlier versions of mobile and fixed communications networks, ASD has found ways to manage risky suppliers by locking them out of providing "core" elements, but its director general has concluded this was impossible to do with 5G where "the distinction between core" and the less significant "edge" of the network is hard to define.

A vulnerability in any single part could jeopardise the entire network.

Threats to Australia's critical infrastructure

Without mentioning China at any moment in his speech, Mr Burgess also planted seeds of doubt about the number of security pressure points that could be applied on Australia's critical infrastructure systems from the rise of high-tech industrial manufacturing in Asia.

The former Telstra executive observed that Australia's openness to trade "changes the industrial base we rely on for critical infrastructure".

"We will need to be open-eyed on the potential threats that any significant change of this kind poses to Australia's most important interests," he said.

Loading

Mr Burgess did not spell out which critical infrastructure drawn from foreign sources could pose a "potential threat", but previous decisions by the Government's Foreign Investment Review Board have halted deeper Chinese ownership of electricity assets as well as prohibiting Huawei from key sections of the National Broadband Network.

His comments suggest Australia may need to be more vigilant about the origins of all technological components within critical infrastructure, which is not only limited to communications and energy but also takes in health equipment, banking, traffic control systems, aviation and food transport and storage.

"5G is just one example of perhaps other technologies we need to think about and understand where those supply chains for those technologies may be and whether or not that represents a risk for us."

If deeper scrutiny is to be applied to technology embedded in other critical infrastructure "supply chains", the ASD chief has suggested Australia would not make those decisions alone, but in partnership with other countries.

Mr Burgess had begun his working career in 1995 at what was once called the Defence Signals Directorate and returned to the agency in January this year.

Loading

Most of its high-tech surveillance techniques, eavesdropping on communications outside Australia, are heavily protected, but the Australian Signals Directorate has recently taken on more public responsibilities advising companies of the risks of cyber attacks.

In a nod to its more open and transparent functions, ASD has even started up its own Twitter account.

Its first tweet quipped: "Hi internet, ASD here. Long time listener, first time caller".