The targets, known as nationally determined contributions (NDCs), must be reviewed every five years. Yet few countries have delivered their updated pledges for 2035.

"We have to admit that we are frustrated," COP30 President Andre Correa do Lago told a press conference in the capital Brasilia.

Brazil, which will host the UN climate summit in the Amazonian city of Belem in November, was among the first to update its NDCs a year ago.

China, the world's largest polluter, followed suit last month.

But many others have missed even the latest September deadline, amid geopolitical and trade tensions that have distracted from climate action.

So far, 62 countries have announced their new climate goals, a number expected to reach 125 by the end of the year, according to Correa.

"It's a bit sad," he admitted.

Conference organizers stressed that the responsibility now falls mainly on the largest emitters, including India and the European Union.

Brazilian Environment Minister Marina Silva also voiced her "disappointment" over delays from "historically allied partners" on climate policy, such as the EU.

"We hope they will submit their NDCs preferably before COP30," she said, so that society can assess "in a transparent manner" whether national targets are aligned with the Paris Agreement goal of limiting global warming to 1.5°C above pre-industrial levels.

COP30 will take place from November 10 to 21, days after a summit of heads of state and government.

According to Correa, delegations from 162 countries are expected to attend the event in Belem, a poor Amazonian city where accommodation prices have soared out of control.

Next week, representatives from 50 countries will gather in Brasilia for a "Pre-COP" meeting aimed at advancing negotiations on the future of global climate action.