European Rugby Cup (ERC) chiefs on Friday called for an end to the public war-of-words over the battle to shape the future of rugby union's European Cup.

Tuesday saw England's Premiership clubs reveal plans for an Anglo-French breakaway competition when the agreement governing the running of both the European Cup and the second-tier European Challenge Cup expires at the end of the current 2013/14 northern hemisphere season.

Clubs from both the Premiership and France's Top 14 are unhappy with the existing set-up which sees nearly all leading sides from Scotland, Ireland, Wales and Italy guaranteed European Cup places on grounds of nationality rather than on their positions in the domestic Celtic League.

However, the Premiership's plan did extend an invitation to teams from beyond England and France to join their proposed new event.

The Premiership and the Ligue National de Rugby (LNR), their French equivalent, are also unhappy at the way European Cup revenues are divided, with the Premiership and tournament organisers ERC involved in a row over the ownership of broadcast rights to matches.

On Wednesday, ERC issued a statement insisting that all parties had "reaffirmed their commitment" to the negotiation process and agreed that "European club competitions must be organised by ERC".

That latter claim has since been disputed by the Toulouse president Rene Bouscatel and Leicester Tigers chairman Peter Wheeler, but ERC remain adamant that such an agreement was reached in Dublin.

ERC independent chairman Jean-Pierre Lux and chief executive Derek McGrath said: "We believe it is now time for ERC's shareholders to cease public ultimatums and to enter into genuine and decisive negotiations aimed at strengthening European club rugby.

"Together we confirm that it was agreed at last Wednesday's Board meeting in Dublin, that ERC, as a signatory to the current Accord, should be involved in all future negotiations aimed at the formulation of a new Accord for the 2014/15 season and beyond.

"To that end, the Board requested that ERC should convene the next, and future, meetings, and that it should consider the appointment of a mediator to move the negotiations forward towards a successful resolution. This process is now under way.

"The Board further agreed that bearing in mind the commitments the company has already entered into, no other structure other than ERC would be appropriate to organise European tournaments going forward."

The ERC's plea for peace came after Wheeler earlier on Friday made it clear he was unhappy with the organisation's stance.

"In support of the personal statement made yesterday by Rene Bouscatel of Ligue Nationale de Rugby (LNR), I would like to say I too was surprised by the press statement issued after the meeting on September 11 2013 of the board of ERC of which I am a member," Wheeler said.

"I would make the following points about the content of this statement. No decision was made by the ERC board to reiterate that European club rugby competitions must necessarily be organised by ERC.

"Secondly, concerning the proposal of some of this board to organise a meeting of the stakeholders, it is the sole right of the individual parties (unions and league organisations) to take a view on any such proposal."

English Rugby Football Union CEO Ian Ritchie joined the appeals for calm discussions, saying: "In what are complex and passionate on-going negotiations concerning the future of the European competitions, the RFU is encouraging talks to continue in earnest.

"We are, and always have been, supportive of the Premiership clubs seeking greater meritocracy across the competitions and appropriate financial distribution.

"It is also important to ensure that rugby across Europe continues to thrive and grow. In terms of authorising any future competition, it is critical to see all the confirmed details before being able to assess its merits."