SYDNEY — Papua New Guinea's prime minister has hailed ties with "big brother" Australia in a historic and closely watched speech in Canberra.

James Marape's address to Australia's parliament — the first by a Pacific Island leader — comes as Australia and China race for influence in the region.

It is also nearly the 50th anniversary of PNG's independence from Australia.

"Nothing will come in between our two countries because we are family,"Marape told Australian MPs.

In jest, he added that "one can choose friends, but one is stuck with family forever" and "we have no choice but to get along".

Marape joins an elite list of overseas leaders who've addressed lawmakers in Canberra, including the Chinese President Xi Jinping, former US President Barack Obama, and Indian Prime Minister Narendra Modi.

PNG is Australia's nearest neighbour. The two nations are separated by just a few kilometres of sea in the Torres Strait where the Pacific and Indian Oceans meet. It is the only country that can be seen from Australia's shoreline

There are two main undercurrents to Marape's visit. Firstly, there's unrest at home sparked by a strike by police officers, which has destabilised his government and could potentially lead to a motion of no confidence in his leadership within days.

Then there's China, and its growing ambitions in the Pacific, which have reignited a diplomatic race with Australia.

In 2021, Beijing signed a security pact with Solomon Islands, a strategically located archipelago north-east of Australia. Canberra has responded, striking accords with neighbours big and small, including PNG, the largest Pacific Island nation.

Marape did not make reference to China in his speech.

He twice emphasised that "a strong economically empowered Papua New Guinea means a stronger and more secure Australia in the Pacific", and concluded by urging Australia to "contribute where you can and leave the rest to us".

It's clear the regional dynamics are changing, said Dirk van der Kley, a senior research fellow at the Australian National University's (ANU) National Security College.

"We [Australia] are used to being the leading economic and security power within the Pacific region and that is probably still true," he told the BBC.

"[But] there is concern in the government and more broadly in Australian society that our ability to shape events in our region may be less than it was previously."

"Australia has been trying hard — prompted by China's rise in the region — to change its behavior. In many cases Australia is out in front of China."

Last November, Canberra announced a security and climate change accord with Tuvalu, a grouping of several low-lying coral atolls in the South Pacific. A month later, Australia reached its security agreement with PNG. But within weeks, PNG's foreign Minister Justin Tkachenko had dropped an apparent diplomatic bombshell when it was reported that his government was talking to Beijing about forging a similar type of deal.

This week,Tkachenko has backtracked, blaming "misinformation" for suggesting a security pact with China was being negotiated. Australia, he insisted, was PNG's partner of choice.

Canberra regards the Pacific as its traditional sphere of influence. China is, geographically speaking, a distant power. So, why is Beijing investing so much time and money in a remote and sparsely populated part of the world?

Kiribati, for instance, is made up of 33 coral atolls spread over 3.5 million sq km of ocean — an area larger than India. It's home to about 130,000 people.

"You are talking about a handful of countries that are spread a long way out from each other with relatively small populations that are relatively poor," saidvan der Kley. "China is trying to increase its influence in the region so that it can shape the global order."

It's part of a strategy to undermine Taiwan, experts say.

"The diplomatic dividend of having strong relations with PNG and other Pacific countries is very important for China partly as it seeks to erode international diplomatic support for Taiwan," said Mihai Sora, a research fellow at the Lowy Institute, a research organisation based in Sydney.

In January, Nauru, a small Pacific republic, re-established formal diplomatic relations with China after severing ties with Taipei, boosting support for Beijing in international forums. At the UN, a vote cast by Nauru (population 13,000) is equal to that of the US (population 333 million).

China also sees opportunity in Papua New Guinea's rich reserves of natural resources, including gas, minerals, fisheries and forestry.

But perhaps the unbreakable relations between Indigenous Torres Strait Islanders who live on the tip of Queensland and their cousins to the north will give Australia an advantage in the race for influence and alliance.

"Culturally and socially they are completely intertwined. It would be impossible to delineate where one kinship network begins and ends," Lowy Institute Pacific Islands project director Mihai Sora told the BBC.

"The communities in the far north of Australia with their counterparts across the sea in Papua New Guinea have a unique governance framework that manages the travel between the two halves of the same cultural group."

Australian Prime Minister Anthony Albanese said the two countries could not be closer.

"Neighbours and mates, partners and equals," he told parliament. "Today, our government is partnering with yours to build the architecture of peace and opportunity. We embrace each other as equals." — BBC