United Nations Secretary-General Antonio Guterres on Thursday warned that power is prevailing over law globally and called for the acceleration of multipolarity.

"The law of power is prevailing over the power of law. International law is trampled. Cooperation is eroding. And multilateral institutions are under assault on many fronts," the UN chief told a start-of-year press conference.

"We are living in a world where actions – especially reckless ones – are provoking dangerous reactions," said Guterres. "They are being multiplied by geopolitical divisions and magnified by an epidemic of impunity."

"When perilous actions do not meet an adequate reaction, the system destabilizes. Impunity is driving today's conflicts – fueling escalation, widening mistrust, and kicking the doors open for powerful spoilers to enter from every direction," he said.

Guterres called for a revamp of the current system to address global challenges, particularly through the strengthening of multilateral institutions.

"As I look across the spectrum of global challenges, one truth becomes unmistakably clear: our systems of global problem-solving face a reckoning. Those systems are out of time. They still reflect the economic and power structures of 80 years ago. But the world is moving on," he said.

"Yet our structures, our institutions, our assumptions, our habits of cooperation remain tethered to another time. This must change," he said.

Guterres said that global problems will not be solved by one power calling the shots or by two powers carving the world into rival spheres of influence.

"It is important to accelerate, deliberately and with determination, multipolarity – one that is networked, inclusive by design, and capable of creating balance through partnerships," he said.

"But multipolarity, by itself, does not guarantee stability or peace," said the UN chief, adding that there is a need for strong multilateral institutions where legitimacy is rooted in shared responsibility and shared values.

"Structures may be out of date, but values are not," he said.

The values enshrined in the UN Charter are the sine qua non of lasting peace and enduring justice, he said. "Despite all the hurdles, the United Nations is acting to give life to our shared values. And we won't give up."

The United Nations is determined to choose actions that generate concrete and positive reactions – reactions of peace, of justice, of responsibility and of progress in the troubled times, said Guterres.