World Rugby vice-chairman Agustin Pichot admits there is only a slim chance that the proposed World League competition will be ready to begin in 2020.
The proposed structure of the 12-team competition was revealed by the Herald last week, with hopes that it would be run from as early as next year.
However, speaking to Radio Sport's Jim Kayes, Pichot said that timeline was very doubtful.
"I'm not confident at all at the moment," Pichot said of the World League starting next year. "We have a lot of tidiness to do; we have a lot more to speak to and to clear. I'm surprised that in this age we are not proactive enough in our communication levels. We should be telling of what we are doing, we should be open and transparent.
"Hopefully we can get there and if we don't get there then it's going to be clear why we aren't."
Initial reports suggested the League would be contested by the teams that make up the Six Nations and the Rugby Championship, with Japan and USA joining the latter.
However, the proposal was heavily scrutinised online due to the apparent lack a second tier tournament and a promotion-relegation system, as well as no Pacific nations being included.
"We are still struggling with the format of the competition and promotion-relegation," Pichot admitted.
South American Rugby boss Sebastián Piñeyrúa echoed the need for a promotion-relegation set up should the new format go ahead to give emerging nations a platform on which to get regular rugby and improve their game.
"Rugby must be honest with itself and decide if it wants to grow and work seriously with its regions in order to conquest and develop big new markets in Europe, such as Spain and Germany, in Latin America with Brazil and Mexico, and Asia with China as an example; or if it wants to continue playing the same eight teams in the finals at the Rugby World Cup," he told the Herald.
"Having a tournament with two tiers, with promotion and relegation, is crucial moving forward towards a global game whilst motivating rugby fans all over the world."
Pichot also addressed Kieran Read's concerns that if the teams had to play more tests, they should at least by meaningful matches; using the development of Argentina as a prime example.
Argentina joined New Zealand, South Africa and Australia in the Rugby Championship in 2012 and since that time they've emerged as a challenging match up.
"That's the key issue, having competitive teams there. At some stage you have to take that risk that Fiji would be competitive, or whoever would be in those positions to amplify the Rugby Championship if we go that road," Pichot said.
"Having New Zealand, Australia and South Africa help Argentina to make sure they were competitive, that's what this is all about. It's not going to be easy, I agree.
"I would like to have the risk of taking that on board, because as long as you carry on playing and have good structures you can be competitive and that will make other teams underneath to be inspired to be competitive and make growth in the global game to have a 24 team world cup and then we are really talking about expanding and being global."