All Blacks and Australia insist that Pacific Island nations and emerging European sides must be included in 'World League'
Rugby heavyweights New Zealand and Australia said on Friday that any shakeup to the international calendar must include chances for developing nations to play meaningful test matches.
Global rugby was in uproar on Thursday when details of a proposed 'World League' involving 12 teams and no promotion or relegation were published by New Zealand media.
Reports said the proposed competition would be limited to established Six Nations and Rugby Championship sides along with the United States and Japan.
'Tier Two' emerging European and Pacific nations, however, would be excluded from the competition for at least 12 years.
New Zealand Rugby (NZR) chief executive Steve Tew denied any format had been agreed, and said the Tier Two nations needed to be included in discussions.
"We certainly need a pathway for teams that don't make the original cut," said Tew.
"We've made it very clear our position is promotion-relegation (and) in the medium and long-term (it) is going to have to be on the table.
"There must be a pathway for the countries around us to get into the big competitions when they're ready, and the same can apply to emerging nations in Europe."
Rugby Australia (RA) Chief Executive Raelene Castle also backed Tier Two nations' inclusion in the future shake-up.
"The competition model must provide opportunities for the Pacific Island nations and other developing nations to continue to grow and compete with Tier One nations," she said in an RA statement.
"While these discussions are progressing with ... World Rugby and the national unions, nothing has been agreed or finalised."
Players criticised the proposal on Thursday, raising concerns over workload, increased long-haul travel and a lack of opportunities for Tier Two nations.
Castle, however, said player welfare issues were "front and centre" in the "robust" discussions.