Brazilian President Luiz Inacio Lula da Silva accused Donald Trump on Friday 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 organization, where a permanent seat costs $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.
Trump unveiled his "Board of Peace" at the World Economic Forum in the Swiss ski resort of Davos 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 Chinese leader 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 balked at the inclusion of Russian President Vladimir Putin, whose forces are fighting in Ukraine after invading in 2022.
France said the charter as it currently stood was "incompatible" with its international commitments, especially its UN membership.