Brazil wants an agreement reached by midweek, with President Luiz Inacio Lula da Silva to make an unexpected return to Belem on Wednesday in a high-level bid to seal a deal.

After announcing its fast-tracked timeline, negotiators spent a sleepless night producing a first draft on trade measures, demands for greater finance for poorer nations, and the inadequacy of national carbon-cutting pledges.

"As always in this phase of the negotiations, this is a mixed bag," EU climate chief Wopke Hoekstra told AFP in the corridors of the cavernous COP30 venue.

UK climate envoy Rachel Kyte said the draft "feels a little out of balance" but hoped discussions with Brazil could yield a "stronger text".

"The Brazilians have a very aggressive timeline. I think it's putting delegates under a lot of pressure, but there's a chemistry to COPs," Kyte told reporters.

No rest was expected in Belem on Wednesday, with diplomats asked to burn the midnight oil for yet another evening.

The quick turnaround of a clear first draft so early in the climate talks sent a signal that Brazil was confident of landing an agreement soon, veteran COP observers told AFP.

- Tough compromise -

Among other things, the draft underscores the gulf between a broad coalition pushing for a "roadmap" on phasing out fossil fuels and an opposing bloc led by oil-producing countries.

On Tuesday, more than a dozen climate ministers and ambassadors united on stage in a call for stronger language in the final agreement on exiting coal, oil and gas.

"The current reference in the text is weak, and it is presented as an option. It must be strengthened and adopted," said Tina Stege, climate envoy from the low-lying Marshall Islands, flanked by counterparts from Sierra Leone, the UK and Colombia.

The draft also suggested tripling financial assistance from wealthy countries to developing ones for adaptation to climate change by 2030 or 2035 -- a key demand from poorer nations.

"Climate finance is not charity. It is a legal and moral obligation," Vanuatu's climate change minister, Ralph Regenvanu, told the summit.

Brazil is eager to show that the world is still united in the fight against climate change, despite the United States skipping the summit and many other nations juggling competing priorities.

"We must show the world that multilateralism is alive," Josephine Moote, permanent representative of the small-island state of Kiribati, told COP30.

But Kenya's climate secretary Deborah Mlongo Barasa said the obligation of rich countries to deliver promised financial assistance "remains the defining test of global solidarity".

Hoekstra said there was "zero appetite" for reopening a debate over climate finance -- a difficult subject that turned acrimonious at last year's COP29 in Azerbaijan.

He also rejected some of the draft proposals on trade concerns as China leads a push against "unilateral" measures and, in particular, the EU's carbon price on imports.

"We're not going to be lured into a phoney conversation about trade measures. Let's call this what it is," he said.

- Presidential push -

In a surprise move, a Brazilian presidential source told AFP that Lula would return to Belem on Wednesday in what many interpreted as a tactic to push through a deal.

"It would be a way of putting pressure on delegates to move quickly to resolve issues," David Waskow, international climate director at the World Resources Institute think tank, told AFP.

The marathon climate talks are supposed to end Friday after close to two weeks of negotiation, but previous summits have frequently run into overtime.