England's Aviva Premiership clubs have reaffirmed that they want "immediate action" to put in place a new European competition for next season.
Their stance follows a meeting on Wednesday of Premiership Rugby shareholders.
English and French clubs are seeking structural, qualification and financial changes to the Heineken Cup and Amlin Challenge Cup competitions after an existing tournament agreement expires next summer.
Exasperated at what they view as a lack of progress by European Rugby Cup over establishing a new accord - the next meeting is not scheduled until October 23 - Premiership Rugby and France's Ligue Nationale de Rugby say they they will establish their own format next term and that teams from other nations were welcome to join.
"On September 10 2013, Premiership Rugby issued a statement confirming that the English and French clubs were instigating new competitions after the conclusion of unsuccessful ERC negotiations," Premiership Rugby said in a statement.
"The clubs see no purpose in new discussions starting as late as the end of October 2013, as proposed earlier this week.
"The proposals from the French and English clubs for two new, strong competitions of 20 teams in each were tabled more than a year ago.
"The clubs reaffirmed their instruction to Premiership Rugby to take immediate action to put in place a competition for the 2014/15 season onwards to include the French and English clubs, and for this competition to be open to teams from other countries.
"It was confirmed that this should be progressed with urgency."
International Rugby Board chief executive Brett Gosper, meanwhile, said on Wednesday that all European nations must be involved moving forward.
"Our clear position is we support a full European competition, and our desire is it's a bona fide European competition," Gosper said.
"We are urging all parties to get together and find a resolution because we obviously believe it is in the interests of rugby to have a strong European competition. It's good for the clubs and good for the unions.
"Hopefully they are in a negotiation, some say they are, some say they aren't, but certainly we believe in a European competition and will support that outcome as much as we can."
And England's 2003 World Cup-winning fly-half Jonny Wilkinson has thrown his support behind the Heineken Cup, declaring its demise would be an "incredible shame".
Wilkinson kicked 11 points as Toulon edged Clermont Auvergne 16-15 in last year's final in Dublin.
"It would be an incredible shame if we weren't able to compete in the Heineken Cup which is, effectively, the World Cup for European clubs," Wilkinson told the Evening Standard.
"Having fought like mad while at Newcastle and twice managing to get into the Cup, and reaching a quarter-final in Paris and having a couple of goes here at Toulon, it makes you realise what an event it is for northern hemisphere rugby.
"Going to the quarter-final, semis and the final with Toulon reminded me so much of that World Cup experience where you have media in the week and stadium visits.
"It's a fabulous thing and the more people who can experience it, the better.
"However, if there is unhappiness and unrest then it needs to be sorted out and long may the competition continue."