Australia and New Zealand are set to sign a wide-ranging security pact with South Pacific nations in September, amid growing concern about nations such as China expanding ties in the region.

The agreement, due to be signed at the Pacific Islands Forum in Nauru, is expected to coordinate disaster response and defence cooperation among the forum's 18 countries.

Australia's International Development Minister, Ms Concetta Fierravanti-Wells, told The Australian yesterday that the pact would bolster security cooperation and "provide a framework for responding to emerging threats".

The agreement, in the making for some time, upgrades a similar pact signed in 2000. But it follows heightened concern in Australia and New Zealand about China's conduct.

A report released by the NZ government yesterday explicitly warned about China's growing influence, saying it could affect stability in the region.

The Strategic Defence Policy Statement, released by the NZ Defence Force, warned that China's growing regional clout threatened the "values championed by the order's traditional leaders". It explicitly noted that NZ and Australia may struggle to retain their influence in the South Pacific as "new players" emerge in the region.

"Increasing challenges to Asia-Pacific security, including the undermining of the existing regional order, could impact New Zealand's security and prosperity," the report said.

"New Zealand's national security remains directly tied to the stability of the Pacific. As Pacific island countries' relationships with non-traditional partners continue to develop, traditional partners such as New Zealand and Australia will be challenged to maintain influence."

Australia and NZ have traditionally been the dominant nations in the South Pacific but have become concerned about China's growing ties in the region.

According to analysis by the Lowy Institute, China provided US$1.8 billion (S$2.4 billion) in aid and loans to South Pacific nations between 2006 and 2016. Australia, the Pacific's largest donor, plans to provide A$1.3 billion (S$1.31 billion) to the region this year.

Australia's Home Affairs Minister, Mr Peter Dutton, said the new pact was not targeted at China but was aimed at improving local ties.

"China is reaching out across the world including into our region," he told ABC News. "But in our neighbourhood, we have a responsibility to work with our neighbours."

In recent months, there has been heightened concern about China's role in the region.

Australia last month announced plans to pursue a security treaty with Vanuatu, just weeks after media reports that China was looking to build a military base there. Both China and Vanuatu vehemently denied the reports.

Canberra also agreed to fund an underwater telecommunications cable linking the Solomon Islands to Australia and Papua New Guinea in an apparent move to block Chinese firm Huawei from developing the project.

Dr Graeme Smith from Australian National University, who is an expert on China's engagement with the Pacific, said he believed the new security pact - called Biketawa Plus - was not directly prompted by worries about Chinese regional influence. But he said it would allay concerns in Canberra about the growing involvement of other players in the South Pacific.

"China is not the only external factor on the horizon," he told The Straits Times. "You have had the Russians and the Georgians running around the Pacific. And in the future, you will have India."

Dr Smith said Pacific nations tended to appreciate Australian military cooperation and training. Unlike the more hands-off approach offered by China, he said, Australia allowed direct training and integration with the Australian troops.

Australia's outgoing defence chief, Air Chief Marshal Mark Binskin, said yesterday that he did not believe any foreign nation had a reason to establish a military presence in the South Pacific.

"If you're looking to guarantee food security, warships are not the way to do that," he told Fairfax Media.

"You are better off working as part of the community, help the communities grow their ability... to provide food, make sure that fishing is sustainable in the waters."

His message to any nations planning to increase their presence in Australia's neighbourhood was: "Don't destabilise the region."