Five major Pacific ports have joined an Australian alliance to boost industry investment and trade amid growing international concerns over Beijing's presence and influence in the region.

The ports, which include Fiji Ports Corporation, Samoa Ports Authority and the Solomon Islands Ports Authority, have signed up as external associate members of peak industry group Ports Australia to formalise maritime sector ties across the region.

Ports Australia CEO Mike Gallacher labelled the tie-up "a massive step forward" in connecting the sector across the region.

Lyttleton Port Company, the largest port in the South Island of New Zealand, and the Port of Napier in the North Island have also signed on in what Ports Australia chief executive Mike Gallacher labelled "a massive step forward" in connecting the sector across the region.

Australia, along with the United States, Britain, New Zealand and Japan, is actively expanding its diplomacy with its "Step Up" program in the Pacific, as Beijing-funded infrastructure projects on many of the tiny island nations threaten to destabilise relations in the Indo-Pacific.