The long-mooted idea would unite club rugby in the British Isles into one competition.
The loss of London Irish, Worcester Warriors and Wasps in the last 13 months has highlighted financial problems in the English domestic game, with the top-flight Gallagher Premiership now containing just 10 teams.
The four Welsh regions have also had their funding cut for the new season of the United Rugby Championship (URC), which features competing teams from Ireland, Scotland, South Africa and Italy.
Sweeney is currently helping to negotiate a new Professional Game Partnership (PGP) between the Premiership and RFU that it is hoped will solve many of the issues ailing the English game.
But while suggesting that plans were pressing ahead on that front ahead of a potential implementation next summer, the RFU CEO confirmed that he had engaged in “hypothetical” discussions about a British and Irish league.
“I think you’d expect us to talk about anything really, the way the game needs to grow, the game needs to be financially stronger,” Sweeney explained.
“We want to attract more investment coming in, so all sorts of conversations take place in terms of different options. That one’s not fully developed by any means.
“So it’s a very tentative, hypothetical conversation at this stage but it has certain merits, but it also has certain challenges. It doesn’t affect the PGP, we will go ahead with a PGP in parallel, and just do that. But it’s one of a number of things that people talk about in terms of how do you take the game forward.”
“It is fraught with challenges, I tend to think about look what happened in football with the European Super League, so fans are going to be taken into consideration on this. What does that mean in terms of the overall structure?
“Some very big, significant questions are going to be asked on it, which is why I say at this stage, it’s very tentative but we consider all conversations.”
The next couple of years are likely to see the introduction of a “Premiership Two” to replace the Championship as the RFU looks to maximise the efficacy and revenue of the second tier.
This may include a return for the three rugby brands lost from the Premiership this year.
Wasps announced on Monday that they were exploring the possibility of building a new permanent home near Swanley in Kent.
The south east of England produces a significant number of players but does not currently have a team in the top two tiers of English rugby, and Sweeney believes bringing a professional club area would be a good idea.
“I was very heavily involved with [new Wasps owner] Chris Holland during the whole process where the club went into insolvency,” Sweeney said.
“I haven’t had a conversation with him recently about the plans to move to Kent. I do know that when research was done in terms of catchment areas, that’s one of the best locations from a fanbase perspective and the development of a sound business plan. I’ll contact him when I get back.”
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies