The Irish, Scottish, Welsh, French and Italian rugby unions have released a joint statement announcing that the European Cup will go ahead next season under the existing European Rugby Cup auspices.
The statement confirms that tournament will go ahead with 20 teams "no matter how many countries are involved".
It said the common aim is to move eventually towards the integration of European competitions within all-encompassing European rugby framework and it will be supported by the ERC.
The joint statement read: "All five Unions believe that it is critical to the interests of the game in Europe that the Unions are at the heart of the governance of cross-border club competitions given that rugby in each country is organised in a pyramidical structure.
"Clubs, provinces and regional organisations form an integral part of the development of the game throughout this structure, from grassroots to the international game.
"Cross-border club competitions must not conflict with the development of the sport in Europe by Unions, this being in the best interest of players, spectators and the sport in general."
Premiership Rugby, the umbrella organisation for the leading English clubs, has consistently said it no longer recognises the ERC and will not participate in competitions under its jurisdiction.