They follow national governing bodies in the United States and Switzerland in formally resigning from the IBA, which last month became the first-ever International Federation to be expelled from the Olympic Movement due to issues with finances, governance and the credibility of competitions.

The IBA, formerly AIBA, had been suspended since 2019 and was stripped of involvement at the Tokyo 2020 and Paris 2024 Olympics.

Boxing New Zealand President Steve Hartley has been among the biggest critics of the IBA under its Russian head Umar Kremlev, and he had indicated its intention to join World Boxing in May.

It had been one of four National Federations suspended by the IBA earlier that month for ties to World Boxing.

Hartley confirmed Boxing New Zealand has now received formal approval from its members to leave the IBA and intends to join World Boxing.

"The Boxing New Zealand membership has voted to leave the International Federation IBA," he said.

"The members of Boxing New Zealand no longer recognise the IBA as our International Federation.

"An application to join World Boxing will be processed as soon as possible."

World Boxing has welcomed the Boxing New Zealand decision.

"Following the recent decision by the IOC Session to withdraw recognition of IBA, all National Federations have a critically important choice to make if they want boxers from their country to have the opportunity to compete at the Olympic Games at Los Angeles and beyond," a spokesperson told insidethegames.

"We are working on numerous applications from National Federations around the world and we warmly welcome the decision by Boxing New Zealand to join other countries in seeking to become a member of World Boxing.

"We urge every National Federation that cares about the future of the sport to support World Boxing in our efforts to ensure boxing remains at the heart of the Olympic Movement."

The Argentinian Boxing Federation has since become the fourth governing body to withdraw from the IBA, which it has blamed on the International Federation's expulsion by the IOC.

Argentinian Boxing Federation President Luis Arturo Doffi and secretary Roberto Rilo informed Kremlev and the IBA of the decision via a letter.

"During the meeting of the Board of Directors of the Argentinian Boxing Federation, where the recommendations and the decision, that the IOC has taken, have been analyzed (sic) and having considered the recommendations of our Olympic Committee, the Argentinian Boxing Federation has decided to terminate our membership within IBA with immediate effect," the letter seen by insidethegames read.

"Unfortunately, IBA and AMBC [the American Boxing Confederation] could not find a solution in line with the IOC's recommendations and thus avoid this total failure in the eyes of our athletes and the Olympic Family, being the first International Federation, which was expelled."

insidethegames has asked the IBA for a comment on the two withdrawals.

It is not immediately clear whether the Argentinian Boxing Federation will seek World Boxing membership.

Its withdrawal from the IBA is the more surprising of the two as publicly it had not been as vocal in its criticism of Kremlev's leadership as New Zealand, although Argentina did take part in boycotts of the Women's and Men's World Championships earlier this year.

Doffi had been elected unopposed as Argentinian Boxing Federation President earlier this year, becoming its first permanent head since the deaths of former AIBA vice-president Osvaldo Bisbal and Luis Romio in 2021.

Boxing New Zealand chair Keith Walker is already one of 10 members on the interim World Boxing Executive Board.

The Dutch Boxing Federation is another high-profile critic of the IBA and said it would make a decision on its membership after the Kraków-Małopolska 2023 European Games, although it is yet to communicate any such verdict.

Its now-Honorary President Boris van der Vorst was an instrumental figure in World Boxing's launch in April, and serves on its interim Executive Board.

Van der Vorst sought to challenge Kremlev for the IBA Presidency last year, but was wrongly prevented from standing in Istanbul in May by the Boxing Independent Integrity Unit (BIIU) before delegates voted against staging a fresh election in Yerevan in September.

Hartley had sought to stand for IBA Board membership in Istanbul but also had his candidacy blocked on the eve of the election by the BIIU, which claimed the Common Cause Alliance group had broken rules relating to campaigning before the electoral period and collaboration between candidates.

The Court of Arbitration for Sport found van der Vorst should have been able to stand, and Hartley delivered one of the soundbites of the Extraordinary Congress in Yerevan when he warned the IBA risked committing "Olympic suicide" if it voted against a fresh election, which its membership ultimately did by a three-quarters majority.

Relations between the IBA and International Olympic Committee (IOC) have further deteriorated since then, culminating in its expulsion at last month's IOC Session, although it has been confirmed boxing will feature at Los Angeles 2028 despite its absence from the initial programme.

World Boxing is seeking IOC recognition, and plans an inaugural Congress in November 2023.

It has been described by the IBA as a "rogue organisation", and Kremlev has claimed his governing body maintains "ambitious plans to increase prize money" and "develop its pro-style boxing".

The IBA last month sacked secretary general George Yerolimpos shortly before the IOC Session which led to its expulsion, with Chris Roberts taking over as chief executive and secretary general on an acting basis.