UN Chief Antonio Guterres on Monday warned nations that he fears the likelihood of a further escalation in the Russia-Ukraine conflict means the world is heading towards a "wider war".

Guterres laid out his priorities for the year in a speech to the United Nations General Assembly (UNGA) that focused on the Ukraine war, the climate crisis, and extreme poverty.

"We have started 2023 staring down the barrel of a confluence of challenges unlike any in our lifetimes," he told diplomats in New York.

The UN Secretary-General noted that top scientists and security experts had moved the "Doomsday Clock" to just 90 seconds to midnight last month, the closest it has ever been to signaling the annihilation of humanity.

He said he was taking it as a warning sign.

"We need to wake up -- and get to work," Guterres stressed, as he listed his urgent issues.

On top of his list was the war in Ukraine, which is approaching its one-year anniversary.

He warned that "the prospects for peace keep diminishing. The chances of further escalation and bloodshed keep growing."

"I fear the world is not sleepwalking into a wider war. I fear it is doing so with its eyes wide open," the top diplomat expressed.

Referencing conflicts around the world, Guterres claimed that "if every country fulfilled its obligations under the (UN) Charter, the right to peace would be guaranteed," adding that it is "time to transform our approach to peace by recommitting to the Charter -- putting human rights and dignity first, with prevention at the heart."

The UN Chief stressed the need to act with future generations in mind and repeated his call for a "radical transformation" of global finance.

Guterres considered that "something is fundamentally wrong with our economic and financial system," blaming it on the increase in poverty and hunger, the growing gap between rich and poor, and the debt burden of developing countries.

"Without fundamental reforms, the richest countries and individuals will continue to pile up wealth, leaving crumbs for the communities and countries of the Global South," he added.

The UN Development Program estimates that the world has gone back five years in terms of human development, including health, education, and living standards.

Guterres warned that the UN's sustainable development goals are "disappearing in the rearview mirror." 

The 17 goals set in 2015 aim to eliminate poverty, provide food security for all, and supply clean and affordable energy by 2030.

"We have opportunities before us to rescue (them)," said Guterres, who is organizing a summit on the matter in New York in September.

The fight against global warming and "climate ambition" will be at the heart of another summit in September where the UN Secretary-General invited world leaders, but "with a condition."

"Show us accelerated action in this decade and renewed ambitious net zero plans -- or please don't show up," he said, before again attacking fossil fuel producers.

He continued, "If you cannot set a credible course for net-zero, with 2025 and 2030 targets covering all your operations, you should not be in business."

Read more: UN's Guterres: Not optimistic about Russia-Ukraine peace talks