Sportal.co.nz 25.Oct.2013Getty Images
The competition is under threat following plans by English and French clubs to form a breakaway tournament - proposals that have recently been backed by the four Welsh regions.
But new measures have now been agreed by the six affected unions and tournament organisers the ERC after two days of negotiations, though none of the rebel clubs attended the discussions.
A statement released on behalf of independent mediators Graham Mew and Stephen Drymer read: "There is consensus that there should continue to be two professional European club rugby tournaments, with each tournament consisting of 20 clubs.
"The Primary Competition would be made up of 20 clubs, with six each from PRL (Aviva Premiership) and the LNR (Top 14), and seven from the Pro12 tournament. The clubs would come through meritocratic qualification from their respective leagues.
"In the case of the Pro12, there will be at least one club guaranteed from each country.
"In year one, the 20th place would be allocated through a play-off match between the seventh placed PRL and LNR clubs. For the following years, the 20th club would qualify through play-offs between the seventh placed PRL and LNR clubs and the two next non-qualified Pro12 clubs. The winner of the secondary competition would qualify to participate in the play-offs, if not already qualified by right.
"The Secondary Competition would consist of up to 20 clubs made up of the remaining 18 PRL, LNR and Pro12 clubs. Two places could be allocated to clubs qualifying from a third competition."
The affected parties have agreed to meet again within the next 10 days to discuss the implementation of the plans, along with operational and management issues.