The move comes following years of speculation as to how and when Argentina would be invited to take part in either the Tri Nations or Six Nations having at one stage risen to third in the IRB World Rankings.
Argentina now have just under three years to prepare for their induction into the current Tri Nations, with conditions surrounding media rights and player availability needing to be met.
Under the terms of the new agreement, the Pumas must make their best players available for the duration of the competition, with the Australian, New Zealand and South African rugby unions stressing that they hope those players will ply their trade in the new Super 15 tournament.
This would mean encouraging many of the top Argentine players to follow former Stade Francais hero Juan Martin Hernandez in moving from European club rugby to the southern hemisphere equivalents (in his case the Currie Cup with Natal Sharks).
"This exciting development will be vital to grow the game in Argentina. This is historic and everyone in Argentina should be proud," said former Pumas scrum-half Augustine Pichot who is now a member of the the Argentine Union's high performance board.
"I can't express the joy of myself and the team that has been working on this project to get to this point.
"We are delighted to have the chance to become a great rugby nation and to play in top-level international rugby and we are committed to working with SANZAR to meet the conditions."
Those sentiments were echoed by acting managing director of SA Rugby and CEO of SANZAR Andy Marinos, who believes Argentina's addition to the Tri Nations concept will be a huge boost for everyone involved.
"To have the Pumas, third at Rugby World Cup 2007 and currently ranked sixth in the world, join with the three top ranked international teams in world rugby will be exciting for fans, players, sponsors and broadcasters across our four countries and beyond," said Marinos.
"They play a different style to the All Blacks, Springboks and Wallabies and their inclusion will see the Tri Nations evolve to be a truly Southern Hemisphere Championship.
"With the significant progress the UAR (Argentine Rugby Union) has made in transforming rugby in Argentina and making the case to SANZAR for it to be included in the Tri-Nations, we are confident that SANZAR, the UAR and the IRB can work together to confirm the Pumas participation from 2012."
If given the official go-ahead, the new Four Nations tournament will be played on straightforward home and away basis, with each side playing a total of six games.
There will be 12 matches in all and the tournament will be played from mid-August to early or mid-October.