United Nations Secretary-General Antonio Guterres said on Friday that the world was facing the risks of conflict as divisions between nations widen, in a warning ahead of a G20 leaders summit.
"If we are indeed one global family -- we today resemble a rather dysfunctional one", Guterres told reporters in New Delhi.
"Divisions are growing, tensions are flaring up, and trust is eroding -- which together raise the spectre of fragmentation, and ultimately, confrontation."
The Group of 20 major economies currently consists of 19 countries and the European Union, making up about 85 percent of global GDP and two-thirds of the world population.
But deep disagreements on Russia's war in Ukraine and how to help emerging nations tackle climate change are expected to hamper agreements during the two-day meeting in New Delhi.
"This fracturing would be deeply concerning in the best of times, but in our times, it spells catastrophe", Guterres added.
"Our world is in a difficult moment of transition. The future is multipolar, but our multilateral institutions reflect a bygone age.
"The global financial architecture is outdated, dysfunctional, and unfair. It requires deep, structural reform -- and the same can be said of the United Nations Security Council."
China's Xi Jinping will miss the G20 meeting at a time of heightened trade and geopolitical tensions with the United States and India, with which it shares a long and disputed border.
Diplomatic opprobrium and war crimes charges are also keeping Russian leader Vladimir Putin away, although Moscow continues to press allies to water down international condemnation of its invasion of Ukraine.