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 in a press conference.

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

Under United Nations rules, a winner can only be chosen by consensus -- meaning 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 its low-lying Pacific islands neighbours, which occupy one of the most climate-threatened areas of the planet.

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."

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.