UN Secretary-Guterres Antonio Guterres said Saturday that a "more inclusive" multilateralism is needed to meet current challenges.

"We saw our multilateral institutions ailing – unable to respond to contemporary challenges, let alone those of tomorrow," Guterres said at the opening of the Summit of the Future's Action Days.

He said the world is in "trouble and torn apart" by conflict and inequalities, threatened by climate chaos and unregulated technologies.

"We need multilateralism that is more inclusive, more effective and more networked with stronger links between international institutions and with the people.

"That means greater representation in developing countries, and it means a stronger voice for all of you and what you represent," he said.

He said governments have "primary" responsibility. "We will not solve today’s global problems without contributions from all of society."

A renewed multilateralism will not be built in a day or by governments alone, he said, while addressing attendees, including world leaders, legislators, academics, artists and activists.

"It will be fueled and carried forward by all of you and the groups you represent. We have fought for ambition. Now let’s fight for action together," he added.