He also reiterated that he was "deeply concerned about the violent repression in Iran," ahead of an emergency Security Council meeting on the crisis scheduled for later Thursday.

Guterres, who will step down at the end of 2026, was giving his last annual speech setting out his priorities for the year ahead and said the world was riven with "self-defeating geopolitical divides (and) brazen violations of international law."

He also slammed "wholesale cuts in development and humanitarian aid" -- an apparent reference to deep cuts to the budgets of UN agencies made by the United States under the Trump administration's "America First" policies.

"These forces and more are shaking the foundations of global cooperation and testing the resilience of multilateralism itself," Guterres told the General Assembly.

"At a time when we need international cooperation the most, we seem to be the least inclined to use it and invest in it. Some seek to put international cooperation on deathwatch."

Guterres said the UN is "totally committed in the cause of peace in Gaza, Ukraine, Sudan and far beyond and tireless in delivering life-saving aid to those so desperate for support."

Those three deadly, protracted conflicts have come to define Guterres's time at the helm of the UN, with critics arguing the organization has proved ineffective at conflict prevention.

Trump has questioned the UN's relevance and attacked its priorities. The organization's top decision-making body, the Security Council, is paralyzed because of tensions between the United States and Russia and China, all three of which are permanent, veto-wielding members.

"As we meet today, the snares of conflict have trapped millions of members of the human family in miserable, prolonged cycles of violence, hunger and displacement," Guterres said.

On Gaza, the UN chief called for humanitarian aid to "flow unimpeded" and on Ukraine he said "we must spare no effort" to stop the fighting.

He also called for the resumption of talks to bring about a lasting ceasefire in Sudan.

Guterres also used his wide-ranging remarks urge action against the abuse of artificial intelligence, to call for efforts to fight inequality.