World Cup semi-finalists Argentina should be included in the Tri-Nations competition, according to International Rugby Board chairman Dr Syd Millar.
Argentina have reached the semi-finals of the Rugby World Cup
"I think Sanzar (the umbrella body for the Tri-Nations teams) are now seriously considering it," he said.
"There is no room for them in the Six Nations, there is no space.
"They are a southern hemisphere country and we continually ask the Tri-Nations to look at it, but they have contracts in place for television and so on."
The Pumas have risen to fourth in rugby's world rankings and have beaten three Six Nations sides - France, Ireland and Scotland - to reach their first World Cup semi-final, where they will take on the Springboks on Sunday.
The South Americans are keen to join either the Tri-Nations event with South Africa, New Zealand and Australia, or the northern hemisphere's Six Nations in order to get regular top-class competition.
"After the Pumas' performances in the Rugby World Cup, you can't neglect them any more," added Millar.
"I also think it would freshen the Sanzar tournament to have another country in it - maybe two, maybe another one from the islands. And they know that themselves.
"But those things are in the hands of other organisations, not ours. We can just simply try to put pressure on them.
"Maybe it will be 2010, but it's up to them. It's also tied up with the Super 14 competition. Like everything else, it is evolving."
It's not long ago that the press were saying it is a nonsense having Portugal in the World Cup
The IRB will decide next April on the structure of the 2011 World Cup in New Zealand, principally whether it should remain at 20 teams or be streamlined to 16.
Critics of a larger competition argue that mismatches between the minnows and the top-tier nations devalues the product.
But the smaller teams gain financially from the tournament, which in turn helps with development, and countries such as Fiji, Tonga and Georgia have impressed at this World Cup.
"New Zealand tendered for the World Cup on the basis of there being 20 teams," added Millar.
"But we have to sit down and look at it in the cold light of day, and not make a knee-jerk reaction.
"It's not long ago that the press were saying it is a nonsense having Portugal in the World Cup.
"A man who can't change his mind can change nothing. I am quite open about it."