The Rugby Football Union have voiced their "surprise and disappointment" at being excluded from Thursday's meeting of their European counterparts.
The Welsh, Scottish, Irish, French and Italian unions issued a joint statement following talks in Dublin - where RFU were reportedly not invited - confirming that they stand "side by side" in driving a 20-team format overseen by ERC.
Crucially, there was no indication in the statement from the five unions which clubs would participate in a union-run competition but insisted that it would go ahead "with 20 teams, no matter how many countries are involved".
The RFU's absent from the meeting was a result of the refusal of the English clubs', who are represented by Premiership Rugby, insistence on breaking away from the ERC and starting a new competition, Rugby Champions Cup.
RFU chief executive Ian Ritchie was present at the negotiations in October that were attended by all six unions and ended with broad agreement on certain principles. There now however seems to be a rift between the Unions and reports suggest that French clubs are wavering in their support of the new tournament amid pressure and financial incentives from their union.
"We are extremely surprised and disappointed not to be involved," an RFU statement read.
"It is right that the outcomes of the mediated meeting held in Dublin on October 24, which resulted in an agreement for a meritocratic tournament and equitable distribution of revenues, have been reaffirmed.
"It has been clear for some time that governance is a central outstanding issue.
"We remain committed to help facilitate a solution so that a truly pan European competition can continue to thrive for the benefit of players and spectators alike."
Premiership Rugby chief executive Mark McCafferty is adamant the Rugby Champions Cup continues to be backed by the French clubs and Welsh Regions.
"We don't see any evidence of their support wavering. We were working with them on Wednesday on the implementation of the Champions Cup," said McCafferty.
"They certainly say that they've never received a financial offer from the French union and we've taken that on trust.
"They've made it very clear over the last 18 months they won't be involved in any competitions in which the English clubs are not playing
"I'm also confident that the Welsh regions remain in support of the Rugby Champions Cup."