The Irish, Welsh and Scottish Rugby Unions have released simultaneous statements confirming that they will not join any breakaway tournament made up of English and French teams unhappy with stalled negotiations over the future of the Heineken Cup.
"The Irish Rugby Football Union wishes to clarify that its clubs will not be participating in future tournaments which do not have the full approval of the International Rugby Board (IRB) or the relevant National Rugby Unions,” the Irish RFU said in their statement.
"The IRFU and its clubs remain fully committed to the development of a pan European Rugby Competition and we welcome the recent comments made by the IRB Chairman, who confirmed that a pan European tournament remains the goal of the IRB. We are confident this can be achieved
"Our focus now is to work collaboratively with our colleagues across Europe, encouraging all parties to come to the table and engage in meaningful negotiations."
English and French clubs have expressed frustration at what they claim is an unfair qualifying system for the Heineken Cup, the clubs believing that the system is weighted towards teams from Ireland, Wales and Scotland.
The clubs also want a greater share of revenue from the tournament organised by the European Rugby Cup (ERC).
"The Welsh Rugby Union remains fully committed to the development of a pan European Rugby competition. We welcome the recent comments made by the International Rugby Board Chairman, who confirmed that a pan European tournament remains the goal of the IRB," the WRU said.
"The Welsh Rugby Union wishes to clarify that it will not sanction any of its clubs or Regions participating in future tournaments which do not have the full approval of the IRB and the WRU.
"The WRU wants an agreement to be achieved and reiterates its determination to negotiate a new format for the European Cup with all of the stakeholders.
"The WRU's focus is to work collaboratively with our colleagues across Europe, encouraging all parties to conclude our negotiations as quickly as possible."
The SRU supplied a similar statement to Wales and Ireland's governing bodies.
The Premiership and Top 14 teams announced on Sunday the creation of the Rugby Champions Cup, a breakaway from the Heineken Cup, which they plan to be in place by the start of the 2014/15 season. They also opened the cup to the Irish, Welsh and Scottish teams competing in the Celtic League as well as the Italian teams in that league.