France's Top 14 and the second tier, Pro D2, are to be abandoned for the 2019-20 season with no announcement made on whether champions will be crowned.
Meanwhile, quarter-final matches in the European Champions Cup and European Challenge Cup will not be played until September at the earliest.
Both decisions have come after the French government's move to prohibit sport for the next four months amid the coronavirus pandemic.
Clubs have agreed with the Ligue Nationale de Rugby (LNR) to end the Top 14 campaign to ensure next season can start on time, with the move expected to be rubber-stamped by the league's steering committee.
Prior to the abandonment of the Top 14, Bordeaux-Begles were eight points clear of Lyon at the summit as they sought a first title since 1991.
The Top 14 regular season is usually followed by play-offs to determine the eventual champions.
Three of the eight teams in the last eight of the Champions Cup play their domestic rugby in France and, similarly, three of those sides still in the Challenge Cup are Top 14 outfits.
The quarter-final ties were due to be played between April 3-5 but had already been postponed along with the semis and the two finals, which were set to be held in Marseille on May 22 and 23.
European Professional Club Rugby still intends to complete the continental competitions.
With three rounds of action still to play, the delays are likely to impact the start of next season's Champions and Challenge Cups, which are scheduled to start in October.