European Rugby Cup chief executive Derek McGrath is adamant that a Heineken Cup solution could still be found through negotiations.
McGrath said that he had not given up hope and that the "the door is still open" even though French and English clubs have indicated that they would not be taking part in planned talks on October 23 and 24.
Speaking at the launch of this season's Heineken and Amlin Challenge Cup competitions in Cardiff, McGrath encouraged all parties to reconsider their stance and help find a mutually beneficial solution.
"ERC supports and wishes to encourage everybody back to the table," McGrath said.
"There is a lot of activity going on to try to find solutions."
While he was out canvassing support, Premiership Rugby and Ligue Nationale de Rugby are continuing work on a proposed structure for the "Rugby Champions Cup."
"There is still time, but all parties bear a responsibility to find those solutions and walking away is not respecting the obligations to those, in particular, who are not sitting at the table (the fans, the players, the sponsors) who have a significant interest in the future of the competitions," said McGrath.
"We have stated many times that we absolutely believe that we will only find agreement when we have the full engagement of all the parties around the table. We haven't had that yet.
"We haven't had engagement and we haven't had negotiation, which is critical to find progress. The door is still open to find solutions."
Premiership Rugby chief executive Mark McCafferty last week wasted no words when asked to comment on the matter.
"We are certainly not attending the meetings on October 23 and 24 that we have been invited to, and the French clubs aren't either," he said.
"From our perspective, those competitions in their current form are over. We don't have any dispute with ERC, from our point of view, which is why the appointment of a mediator (Canadian lawyer Graeme Mew) by ERC is a bit odd.
"We are putting a competition format and a financial structure in place through the Rugby Champions Cup that is going to be attractive to everyone."
Top English and French clubs are currently serving a notice period to leave European Rugby Cup-run competitions.
Meanwhile Celtic unions Wales, Scotland and Ireland have indicated they would not sanction their teams to play in any tournaments that are not approved by the International Rugby Board.