"There is a huge amount of work ahead for ministers and negotiators. I urge you to get to the hardest issues fast," Stiell told the gathering.

"We absolutely cannot afford to waste time on tactical delays or stonewalling," he said.

Government ministers from around the world have started to arrive in Belem to take over negotiations and try to break the deadlock as the second and final week of talks begins.

Three issues were blocking progress after a week of talks in the Amazonian city:

China, India and other allied countries want COP30 to adopt a decision against unilateral trade barriers -- a dig at the European Union's "carbon tax" on imports of carbon-intensive goods such as steel, aluminum and fertilizers.

Meanwhile, island states vulnerable to rising seas -- backed by Latin American countries and the EU -- believe it is crucial for COP30 to respond to the latest projections showing the world will fail to limit warming to 1.5C and step up their climate commitments.

But major emerging countries, from China to Saudi Arabia, do not want a text that implies they are not doing enough to curb climate change.

The third point of contention is a bid by developing countries, especially from Africa, to point the finger at developed nations for falling short on providing financing to help adapt to climate change and cut emissions.