Andrew Hampton, the spy chief who has blocked Spark's plans to use Huawei for its 5G network, says he has come under no pressure from Five Eyes counterparts or from political quarters in carrying out his role.
He said his role as head of the Government Communications Security Bureau (GCSB) was tightly prescribed by legislation and he was not able to take into account such issues as international relations or the effect on the economy.
But he said there were several more steps in the process at which the decision could be reconsidered, ultimately by the Minister for the GCSB, Andrew Little.
China's Government has criticised the decision, with Foreign Ministry spokesman Geng Shuang saying there was "serious concern".
"We hope the New Zealand Government provides a fair competition environment for Chinese companies operating in New Zealand, and does more to benefit bilateral mutual trust and co-operation," the spokesman said.
Hampton would not comment specifically on the Spark-Huawei case, but he talked about the process generally.
"I can only follow the process that is prescribed in legislation and take into account the types of factors outlined in legislation," Hampton told the Herald today.
"My role as regulator is very specific about the factors as regulator I need to take into account and they are all about 'is there a network security risk here?'
"Wider factors about impacts on the economy, impacts on international relations they are for later in the process and they will be the types of things that the minister would need to take into account if it ever got to that point."
He said that while New Zealand shared intelligence with its Five Eyes Partners – the United States, Britain, Canada and Australia – he had never come pressure in the regulatory function, which the agency has undertaken on hundreds of occasions.
"Whilst we are an intelligence agency and of course share intelligence with our Five Eyes partners, I've come under no pressure from Five Eyes partners when undertaking this regulatory function. It is also a function I undertake independently from ministers as well."
One of the purposes of the Telecommunications (Interception Capability and Security) Act 2013 was to protect New Zealand's most important information networks.
When network operators wanted to make significant changes to their network, they need to notify the GCSB.
"The first thing that my organisation needs to do is determine whether or not there is a network security risk identified. If there is, we need to notify the network operator and they have two options: they either withdraw their notification, or they work with us to mitigate it."
If it was not possible to mitigate it, the next step would be for the Commissioner of Warrants, Sir Bruce Robertson, to look at it and report to Hampton.
"If the issues still aren't resolved, I then have the ability to refer it to the minister responsible for the GCSB to make a final decision," Hampton said.
"The minister takes into account not only the national security issues that I advise on but a broader range of issues and that requires him to consult with other ministers."
Commenting on the Chinese reaction, Foreign Minister Winston Peters suggested at Parliament that China may not have understood the process.
"It is not clear that the Chinese understand there is a process under our law that has begun because of the GCSB statement to Spark," he told reporters. "Until that process has finished, any interpretation they might have would be erroneous."
Any suggestion the Government had banned Huawei was not true and he would be attempting to correct that impression with China.
Peters' colleague Andrew Little also downplayed the diplomatic impact, saying: "I'm confident that the relationship with China is a very broad one and a very robust one."
"We have a very strong relationship," Little said. "This is an issue about New Zealand looking to its national security interests. That is what you'd expect a Government to do. That's what the GCSB has done."