Sportal.co.nz 27.Sep.2013Getty Images
The English Premiership and French Top 14 unveiled plans on Sunday for a breakaway competition after frustrations over qualification and revenue from the current setup.
Inviations were made to the clubs from the Pro12 to join the tournament that is planned to launch in the 2014-15 season, however they have stated their commitment to the competitions already in place.
Clubs from the Pro12 - which includes clubs from Wales, Scotland, Ireland and Italy - have won five of the last eight Heineken Cups and the associated unions confirmed they hold no intention of being part of a competition that does not have International Rugby Board (IRB) approval.
In a joint statement, the three unions confirmed they remain committed to maintaining a tournament that runs across the whole of Europe.
"The (Welsh, Irish and Scottish unions) wish to clarify that its clubs will not be participating in future tournaments which do not have the full approval of the IRB or the relevant national rugby unions," they said in a 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 (Bernard Lapasset), who confirmed that a pan European tournament remains the goal of the IRB.
"We are confident this can be achieved."