Australian Prime Minister Anthony Albanese met his Fiji counterpart in Suva on Wednesday to press Canberra's message that its $245 billion nuclear powered submarine programme does not violate its nuclear non-proliferation commitments.
Australia is party to a nuclear-free zone treaty with 12 other South Pacific nations, including Fiji, in a region where sensitivity over nuclear weapons is high because of the effects of nuclear weapons tests by the United States and France.
The strategically located region has been a focus of rising tensions between the United States and China over Beijing's ambitions to increase its security presence.
China this month renewed its diplomatic push for Pacific island countries to cooperate with Beijing on security, after a proposed 10-nation deal was rebuffed in June.
Albanese met with Fijian Prime Minister Sitiveni Rabuka on Wednesday to discuss regional security, a day after unveiling details of the AUKUS submarine programme in San Diego with the leaders of the United States and Britain.
Australia will buy three US Virginia-class submarines early next decade. British and US nuclear-powered submarines will also be deployed in Australia from 2027.
Australia's defence officials have said the nuclear submarine fleet is needed as a deterrent to China's naval build up.
China has said AUKUS violates a nuclear non-proliferation treaty, which Australia rejects. Australia emphasised on Tuesday the submarines will not carry nuclear weapons.
Beijing's special envoy to the Pacific islands, Qian Bo, sought support this month from a sub-regional group of Fiji, Vanuatu, Papua New Guinea and Solomon Islands for a security training and assistance role for China, a statement from the Melanesian Spearhead Group showed.
Qian has visited Papua New Guinea, Vanuatu and the Federated States of Micronesia in the past fortnight. In a statement on March 10, the leader of the Melanesian Spearhead Group - an intergovernmental organisation of Fiji, Papua New Guinea, the Solomon Islands, Vanuatu and a pro-independence party of New Caledonia - said it would consider security assistance, including training and equipment from China.
"My members have affirmed in very strong terms that no one will choose their friends or enemies for them," MSG Director General Leonard Louma said.
The group's regional security strategy will be agreed upon at a meeting in Fiji in April.
New Zealand's Foreign Minister Nanaaia Mahuta heads to Fiji on Wednesday, while a US delegation led by White House Indo-Pacific coordinator Kurt Campbell will visit Pacific island countries in the coming days, the US embassy in Auckland said.