Three-quarters of Australians believe the country's Navy should follow the United States in challenging Beijing's expanding military activity in the disputed waters of the South China Sea by carrying out so called "freedom-of-navigation" operations, a poll has found.

But underlining the complexity of the relationship with our largest trading partner, respondents to the Lowy Institute annual poll also said China was our "best friend in Asia" (30 per cent) ahead of Japan (25 per cent), and that the relationship with China was now as important as our long-standing alliance with the US (both at 43 per cent).

Lowy's director of polling, Alex Oliver, told Fairfax Media that China's soft power diplomacy push had engendered a "growing familiarity" with Australians, who have long considered China as "very important economically to us".