Paris - The French Football League (LFP) fired a broadside on Wednesday at plans to revamp the Champions League, saying proposed changes would weaken national championships.
The league's board said in a statement it was "deeply concerned" that club finances and playing standards would suffer if plans backed by European football's governing body UEFA went through.
It called for an emergency meeting of the league to take an official stand on the controversial plans.
A revamped Champions League from 2024 would feature four groups of eight teams in the pool phase as opposed to the eight groups of four in the current format, according to media reports.
The top six teams in each group would qualify for the following year's edition regardless of where they finish in their domestic competition, according to reports.
That would mean the role of national leagues would be diminished with France vulnerable to losing one automatic place in the Champions League which currently goes to the team finishing second in Ligue 1.
Dates for the new Champions League would also clash with domestic match schedules.
"The media are not inventing this," the president of Spain's La Liga, Javier Tebas told AFP on Friday.
"The question now is how to block the road taken by UEFA and the ECA (the European Club Association) towards retaining the name of the competition but completely changing its nature."
"No-one can force the leagues to change the format against their will," he said.
More than 900 European clubs have been summoned for talks in Madrid on May 6-7 by an association representing Europe's domestic leagues.
The following day UEFA will hold talks on the project with European leagues in Nyon, the body's Swiss headquarters.