Brazilian President Luiz Inacio Lula da Silva has accused Donald Trump of trying to create "a new UN" with his proposed "Board of Peace".

The veteran leftist joins other world leaders who have avoided signing up for Trump's new global conflict resolution organisation, where a permanent seat costs US$1 billion and the chairman is Trump himself.

"Instead of fixing" the United Nations, "what's happening? President Trump is proposing to create a new UN where only he is the owner," Lula said on Friday.

Trump unveiled his "Board of Peace" at the World Economic Forum in the Swiss ski resort of Davos on Thursday, joined on stage by leaders and officials from 19 countries to sign its founding charter.

Lula defended multilateralism against what he called "the law of the jungle" in global affairs.

His remarks come a day after he spoke by phone with President Xi Jinping, who urged his counterpart to safeguard the "central role" of the United Nations in international affairs.

In his remarks on Friday, Lula said "the UN charter is being torn".

Although originally intended to oversee Gaza's rebuilding, the board's charter does not seem to limit its role to the Palestinian territory and appears to want to rival the United Nations.

Key US allies including France and Britain have also expressed doubts.

London baulked at the inclusion of Russian President Vladimir Putin, whose forces have been fighting in Ukraine since 2022.

France said the charter as it currently stood was "incompatible" with its international commitments, especially its UN membership. (AFP)