Canberra and Ankara are under pressure to break the impasse and avoid a scene in Belem, where Brazil is desperate to show that climate diplomacy still works.

The host must be chosen by consensus, so unless Australia or Turkey withdraws its bid for the 31st UN Climate Change Conference (COP31), or they come to an agrement about sharing the duty, both countries will miss out.

That would be unprecedented and would see COP31 hosting rights default to Germany.

Australian Prime Minister Anthony Albanese on Monday was firmly opposed to the suggestion of co-hosting with Turkey.

"That's not an option, and people are aware that it is not an option, which is why it has been ruled out," he said.

A Turkish diplomatic source told AFP over the weekend that Ankara "continues to advocate a co-presidency model" but was willing to go it alone should consensus not be reached.

Australia is bidding to host the summit in the southern city of Adelaide alongside its Pacific Island neighbours, hoping to cast a spotlight on a part of the world being hammered by the effects of climate change.

Pacific Island leaders have long criticised COP summits for marginalising their voices or offering limited practical solutions.

Australia, with its vast flora and fauna, is also highly vulnerable.

But hosting duties would also draw scrutiny of Australia's green record. The world's second-largest coal exporter has long profited from fossil fuel exports and treated climate action as a political and economic liability.

Australia's "climate wars" -- a years-long domestic fight over emissions policy -- stalled progress and the country remains dependent on its fossil fuel economy for growth.

If the country were to win the COP bid, it would be the first time the Pacific region has hosted the annual meeting.

Turkey wants COP31 to focus on the world's most vulnerable regions, with potential special sessions addressing Pacific issues, the diplomatic source added.

Brazil has appointed a representative to help resolve the disagreement between Australia and Turkey.

But diplomats say that no progress has been made yet toward reaching an agreement before COP30 wraps up on November 21.