Australia’s former ambassador to China has warned that relations between the two countries remain fragile and vulnerable to future shocks.

Graham Fletcher says stability between Canberra and Beijing should not be taken for granted.

He claims Australia has quietly rejected some Chinese proposals to expand cooperation in infrastructure and artificial intelligence.

The former ambassador says major differences in national security and regional ambitions mean the two countries are unlikely to become close partners.

He also warns that disputes over the Port of Darwin and growing competition in the Pacific could further strain relations.

Fletcher says another downward spiral remains possible if serious disagreements between Australia and China cannot be managed.