Toulon joining the Aviva Premiership "doesn't stack up for a thousand reasons" but a European league could become a long-term reality, according to Gloucester chief executive Stephen Vaughan.
Toulon's owner Mourad Boudjellal has written to Aviva Premiership bosses to request that his club be allowed to defect from France's Top 14, and English league chiefs will discuss the idea in further detail.
Rugby Football Union (RFU) chief executive Ian Ritchie branded Toulon's plan "a long shot", with Boudjellal's move already viewed as a bartering tactic aimed at easing the Top 14's newly-imposed salary cap.
"It doesn't stack up for a thousand reasons, it wouldn't get sanctioned by the union or the league," Vaughan told Press Association Sport.
"It would also throw into question the size of the league and the structure, who would get promoted and relegated, because you couldn't have an extra game from a player welfare perspective.
"There are so many ways in which it couldn't really get off the ground.
"I can't see one overseas club joining an existing league, it would have to be a joining-together of nations as per the Pro12 really.
"What Toulon's position perhaps does show however is the wide appeal that the Premiership can boast.
"I think it's the most competitive league. The Top 14 is very strong, but what I like about the Premiership is that you can genuinely say there are probably eight teams at the start of any season hoping and aspiring to finish in the top four.
"I don't think you get that in another league. I would say it's certainly the most captivating and interesting league in my opinion, due to the amount of competitive teams involved."
Ritchie said no one at Toulon has contacted the RFU over Boudjellal's proposals.
"Toulon haven't approached us - I heard about it at the same time as everyone else did on Thursday. It was a bolt out of the blue, there weren't any discussions beforehand," Ritchie said.
"As I understand it - and I haven't had time to go into gory details - the French authorities will have a view on it as well.
"As far as I'm concerned it's still a hypothetical. You have to reflect on it, but it's fair to say it's a long shot.
"I remember Rangers wanted to go into the Football League at one stage a few years ago," Ritchie said.
"In some ways a European League is about chasing the economics and the good thing is that in professional rugby in this country, the economics work pretty well.
"The revamp that we did of the European Cup should hopefully deal with that. People will think about a European league and it's sure to come up again, but the focus is on England."
English and French club bosses' collective muscle-flexing that turned the Heineken Cup into the European Champions Cup significantly boosting television revenue has already led to speculation that a continent-wide league could be in the offing.
Vaughan has refused to rule out a potential radical redrawing of European club competitions in future, but cannot see any short-term shifts.
"I could see it being a possibility," said Vaughan of a potential European league.
"You've got a lot of very influential and aspirational club owners and leaders.
"And it wouldn't be beyond the means of the sport to think that they wouldn't try to form a European league, whether that's one or two tiers.
"It wouldn't surprise me but I certainly don't see it for a number of years."