Premiership Rugby Deputy Chairman Bruce Craig believes that blocking the proposed Rugby Champions Cup would have "catastrophic implications" for Pro12 clubs.
Craig - who is also Chairman of Premiership side Bath - believes that the new competition is the only way to save European clubs rugby.
"If the competition is not approved then that would have absolutely catastrophic implications for Celtic rugby," Craig told BBC Sport.
"Celtic teams would be without significant revenues."
Craig also reinforced Premiership Rugby's refusal to return to negotiations regarding the Heineken Cup, and confirmed there will be no English or French representatives at the next stakeholder meeting on October 23rd.
"The Heineken Cup is finished, it's over. The Rugby Champions Cup is a way to save European Rugby.
"If all 38 European clubs were actually given the opportunity to come into the Rugby Champions Cup, I believe all 38 would probably agree. It's basically the Celtic unions that would stop them from participating.
"Everyone would prefer that we didn't go down the legal route. We all want a competition that is a fabulous European competition.
"The reality though is that if there was to be a blockage there are obvious questions around restraint of trade. This new Champions Cup would generate in the region of 60 to 70 million Euros minimum, which would actually cut out a big percentage of the English and the French clubs' losses."
In addition, Craig is keen to emphasise that the potential financial fall-out for the Pro12 clubs is far greater than for their English and French counterparts.
"The amounts of money that is generated in the English and French games through our domestic leagues accounts for approximately 80 percent of our revenues, so the implication of not playing in a Heineken Cup is much less serious for French and English clubs as it is for the Celtic nations.
"At the moment, for the 2014-15 season there is no European rugby. This competition is one in which all the clubs are invited to play and there will be an equal distribution of money on a per team basis.
"The reality of it is that if the Rugby Champions Cup doesn't happen, then the Celts will not be playing in a competition and they won't have those distributions from that competition.
"People say the English and French clubs are greedy. The fact is we are losing money.
"In terms of sustainability and the future of the game, this is an opportunity for us to increase revenues into the English and French club game which gives it more viability. The unions should be approving that so there is continuity in English, French and Celtic rugby, because if there isn't there would be financial oblivion for the Celtic countries."