Australia relied on its own security advice to ban Chinese companies Huawei and ZTE from the 5G network rollout, former prime minister Malcolm Turnbull says.
He also says he talked with United States President Donald Trump many times about how 5G will change communications and the risk it presents to security.
In a speech to the Henry Jackson Society in London, Mr Turnbull said banning companies who could not meet Australia's security requirements was a necessary step.
"We were the first nation to do so. And we so decided not because another country told us to, let alone for protectionist reasons, but to defend our own sovereignty and to hedge against changing times," Mr Turnbull said on Tuesday in London.
"I discussed this issue with President Trump on many occasions. 5G is different."
Mr Turnbull said he raised concerns with the Five Eyes security alliance - Australia, the US, Canada, New Zealand and the UK - that they did not have a leading 5G vendor based in their countries.
Two of the four leading companies are Chinese, while the other two are Europe-based Ericsson and Nokia.
He said it "beggars belief" the countries that pioneered wireless technology have allowed themselves to fall behind to the point their telecommunications companies were not leading the 5G charge.
Mr Turnbull said advice from the Australian Signals Directorate showed 5G technology would significantly lower the barriers for foreign powers to compromise a network.
The UK is considering its position on Huawei, while New Zealand has banned Huawei from its 5G rollout.
The decision to ban Huawei and ZTE from the 5G rollout was announced just hours before Mr Turnbull announced his plan to resign as prime minister in August, in a media release that did not mention either company by name.
