Fifa's plans to expand the World Cup to 48 teams have been met with fierce opposition from Europe's biggest clubs who say their stars are already playing too many games.
Proposals to expand the World Cup in 2026 from 32 to 48 teams are being backed by Fifa president Gianni Infantino, who favours a format that would divide teams into 16 groups of three ahead of a straight knock-out competition.
Other reform options to be considered at next month's Fifa Council meeting in Zurich include expanding to 40 teams or 48 teams but with a 32-team play-off to decide who joins 16 seeded teams in the tournament as it currently exists.
But Fifa's expansion ideas will face opposition from the European Club Association (ECA), the representative group of the continent's biggest teams that counts Arsenal, Chelsea, Liverpool, Manchester City, Manchester United, Tottenham, Everton, Leicester and Newcastle as members.
In a statement the ECA said that the number of games played throughout the year "has already reached an unacceptable level, particularly for national team players" and that it had written to Infantino encouraging him not to follow through with his plans.
"We have to focus on the sport again," said ECA chairman and Bayern Munich chief executive Karl-Heinz Rummenigge. "Politics and commerce should not be the exclusive priority in football.
"In the interest of the fans and the players, we urge Fifa not to increase the number of World Cup participants."
The ECA has previously been at loggerheads with Fifa over their decision to host the 2022 Qatar World Cup in the winter during the middle of the European domestic season while the dispute over a bigger World Cup has existed for the duration of Infantino's tenure.
Immediately following his election as Fifa president in February, the ECA issued a statement calling on him to drop expansion plans.