Argentina, ranked third in the world, are marginalised by a lack of inclusion in a major annual tournament and formally applied to join the Six Nations earlier this month.
The IRB have devised a four-year plan which will integrate them into the international calendar - with the Tri-Nations their ultimate destination.
'The forum agreed that the Pumas' future lies in the southern hemisphere,' said an IRB statement.
Television rights to the Tri-Nations are to be renegotiated in 2010 and the combined Australia, New Zealand and South African unions are considering plans to expand.
Major logistical problems would arise from Argentina's involvement in a beefed-up Tri-Nations with the main stumbling block being that most Pumas are based in Europe.
But it is planned that this obstacle will be removed by the introduction of a competitive professional structure in Argentina.
'In the short term there are major hurdles to the integration of Argentina into the southern playing structure,' continued the statement.
'However, the Argentinian Rugby Union (UAR) have made a commitment to have their players contracted to the union and for the majority of their players to be based in Argentina by 2012.
'The forum agreed to assist the UAR to put in place pathways to get the players back to Argentina and to develop the next generation of home-grown Pumas.
'This includes looking at new competition structures in Argentina, the Americas and elsewhere.'
Argentina's development will be assisted by their expected admission into the Churchill Cup and the number of Test matches the Pumas play per year will have increased from six to nine by 2010.
This will include two internationals during the Six Nations following the agreement of English and French clubs to release Pumas for the matches.
The forum, which was attended by 90 delegates from all rugby stakeholders, decided the existing rugby calendar would be preserved save for minor modifications.
Moves are also under way to safeguard the integrity of Test matches in November and June, which have become increasingly devalued by weakened touring teams.
Two suggestions are under consideration to address this issue - the introduction of a 'world series' that would give ranking points to existing matches and would culminate in a grand final, and a 12-team pool format run over two years between World Cups.
A cap on the number of Tests played each year to 11 and the agreement of English and French clubs to end their season on May 31 would provide space for any change and enhance the prestige of the November and June internationals.
A stand-down period of at least 10 weeks for players was also agreed to ensure suitable time for rest and pre-season conditioning.