"No, we won't be co-hosting," Prime Minister Anthony Albanese said, arguing that co-hosting "isn't provided for" under the rules of the United Nations Framework Convention on Climate Change.

"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.

Both Australia and Turkey are bidding for COP31 and neither is backing down, creating an unwanted distraction at the ongoing negotiations where Brazil is desperate to show that climate diplomacy still works.

Canberra and Ankara are under pressure to break the impasse and avoid a scene in Belem, a city in the Amazon Rainforest.

A Turkish diplomatic source told AFP on Sunday that the country "continues to advocate a co-presidency model".

The host must be chosen by consensus so unless Australia or Turkey withdraws its bid, or they somehow agree to share the duty, both countries will miss out.

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

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

But it will also draw scrutiny to the green record of a country that has long profited from fossil fuel exports and treated climate action as a political and economic liability.

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