China could use its 1 million expats in Australia to help grow its influence and power in the region, former prime minister John Howard says.

Speaking in London on a panel discussion about the Five Eyes intelligence network, Mr Howard said "Chinese assertiveness" was more pressing than the cyber threat posed by the world's most populous nation.

"China has a massive diaspora in South-East Asia," Mr Howard said.

"Australia's population will reach 25 million soon, 1 million of them are ethnic Chinese.

"[They are] terrific citizens making enormous contributions to our nation, but it remains the case that China is very interested in the capacity to use those people to further her own power and her interests."

Organised by UK think tank Policy Exchange, the panel discussion focused on the importance of the Five Eyes intelligence arrangement between Australia, the UK, US, Canada and New Zealand.

Mr Howard said how intelligence agencies from the Five Eyes nations advise and respond to that assertiveness was "absolutely crucial".

"I don't play down the cyber threat, but to pretend there isn't a game in town involving China particularly in our part of the world … is deluding itself," he said.

The panel also included former Canadian PM Stephen Harper and George Robertson, the former secretary-general of NATO.

Mr Harper said he believed the cyber threat posed the most serious challenge to the Five Eyes nations, and that some of those nations' use of Chinese telecommunications hardware in its infrastructure had worried other partners.

"Different countries have permitted the penetration of Chinese and other hardware in particular, and in some cases software, into our systems in a way that causes some of the rest of us to be reluctant to engage in cyber cooperation," he said.

Mr Harper's comments appear to reference current concerns over Chinese telco giant Huawei, which has involvement in the UK's, Canada's and New Zealand's technical infrastructure.

The US has raised concerns over Huawei's links to the Chinese government while Australia banned it in 2012 from involvement in the National Broadband Network and may block it from taking part in the upcoming 5G mobile network.