The chief executive of the Rugby Players Association has warned global rugby leaders they could face heavy backlash like that experienced last year during the failed Global League proposal should plans go ahead to incorporate South Africa into an expanded Six Nations.
Damian Hopley told Rugby Pass on behalf of England's leading players those looking into the potential of a "Seven Nations" should use World Rugby's failure to introduce the Nations Championship last year as a warning.
"If you look at the failed attempt at launching the Nations Championship by World Rugby, that effectively died a death when seven of the sport's leading captains came out and said it wouldn't work based on player welfare," Hopley said.
"That sent a very clear message that we are all partners in this game and everyone should be afforded that importance when you are talking about how the game operates. Clearly, the players' voices are the most important because you want to make sure you have a team to run out there for the matches."
The International Rugby Players' Council, led by Ireland captain Jonny Sexton, said at the time they disapproved of the global league due to concerns for player welfare, feeling the competition would be putting too much demand on players.
Hopley believes the same kind of stress and demand would be present in a Seven Nations.
"You would expect there would be a strong player consultation going forward as you don't want to go down the same road again because it becomes self-defeating."
The comments follow on from those made by England coach Eddie Jones yesterday who said the inclusion of the Springboks would "decrease the level of competition".
"It's called the greatest rugby tournament in the world and I think it is. So why would you want to add other teams that are going to decrease the level of competition," Jones said.
"I can only talk from experience. Super Rugby was the golden egg of rugby - brilliant, 12 teams, competitive. As soon as it had gone to 14 and 15, it had lost its allure."
"You want the best teams playing against each other. There's something about the Six Nations - because of the history of the relationships between the nations, it makes it more outstanding."
Discussion of the Springboks' move to the Six Nations began on the weekend after reports from the UK suggested the reigning world champions would leave the Rugby Championship after 2023 - a fact New Zealand Rugby has disputed saying South Africa are part of a broadcasting deal with SANZAAR until at least 2025.