Diplomats at the ongoing COP30 conference in Brazil have just days left to settle rival bids from Australia and Turkey.

If neither country agrees to step aside, the COP31 conference will be hosted by default in the German city of Bonn -- an outcome most are eager to avoid.

Prime Minister Anthony Albanese on Tuesday evening gave the first hint he may be willing to back down.

"If Australia is not chosen, if Turkey is chosen, we wouldn't seek to veto that," he told reporters.

There is no official vote to choose the successful hosting bid.

Under United Nations rules, a winner can only be chosen by consensus.

This means that unless Australia or Turkey withdraws, both could miss out.

"The way that the system works is that if there is not agreement and there's more than one candidate, it goes to Bonn," said Albanese.

"There is considerable concern, not just from the Pacific, but internationally as well, that that will not send a good signal about the unity that's needed for the world to act on climate."

Australia has been vying to host the COP31 summit alongside Pacific island neighbours threatened by tropical cyclones and rising seas.

But the government is reportedly split on whether it should forge ahead to host an event that some estimates suggest could cost up to US$1.3 billion.

- Pacific plight -

Albanese said even if Australia stepped back, he would still look for ways to keep the plight of the Pacific on the agenda.

"What we would seek to do is to ensure that the Pacific benefited from that, through measures, potentially like a leaders meeting, to be held in the Pacific."

Following Albanese's comments, an Australian government spokesperson stressed that the nation still had "overwhelming support" as prospective hosts.

"But of course we will continue to negotiate with Turkey in good faith for an outcome in the best interests of the Pacific and our national interest," the spokesperson said.

As recently as Monday, climate minister Chris Bowen said Australia was still "fighting hard" to beat Turkey's bid.

"We don't know how it'll go. But we're in it to win it," he told AFP in Brazil.

Australia has already rejected Turkey's offer to share the presidency, saying it was not feasible to split those complex duties between two distant countries.