UN and security crews rushed with extinguishers to put out the blaze, which tore a hole in the roof of the COP30 site in Belem as smoke engulfed the corridor and people shouted "fire!"

The fire was brought under control and no injuries were reported, Brazilian tourism minister Celso Sabino said. The cause of the blaze was not immediately known.

Firefighters arrived at the scene as smoke billowed inside and out of the conference, which is being held in large tents in the city at the edge of the Amazon, with tens of thousands of people in attendance.

"Firefighters and security teams responded promptly and continue to monitor the site," Brazil's COP30 organizers said in a statement.

The fire started in a country pavilion inside the site's "blue zone" near the entrance of COP30. A light rain caused people outside to cheer.

The fire took place as ministers were deep in negotiations aimed at breaking a deadlock over fossil fuels, climate finance and trade measures, with one day left in the two-week conference.

Mauricio Lyrio, the head of the Brazilian delegation, said he was signing an agreement with a third country when he was asked to leave. He said his team does not believe they will be able to return to the site on Thursday.

- 'World is watching Belem' -

Nearly 200 countries have spent the past two weeks hashing out issues at COP30 -- from a "roadmap" to transition away from fossil fuels proposed by host Brazil, to concerns over weak emissions-reduction plans, finance for developing countries, and trade barriers.

Earlier in the day, UN Secretary-General Antonio Guterres urged negotiatiors to reach an "ambitious compromise."

"The world is watching Belem," he told reporters during a morning news conference, as nations awaited a new draft negotiating text before the summit officially closes on Friday evening.

"Communities on the frontlines are watching too -- counting flooded homes, failed harvests, lost livelihoods, and asking how much more must we suffer?"

"Please engage in good faith," he said.