Top European football clubs and championships are stepping up a campaign to block efforts to move the 2022 World Cup in Qatar to the winter months.
FIFA wants to move away from the traditional summer tournament to avoid the searing temperatures in the Gulf state. But that would force Europe's top championships to take a costly six week break.
The Association of European Professional Football Leagues (EPFL), at a Congress in Stockholm, called for the 2022 tournament to be kept in the summer.
British media said the European Club Association (ECA), which groups 214 top clubs, including Real Madrid, Manchester United and Bayern Munich, may press for the Qatar World Cup to be held in May.
Broadcasters in various parts of the world have also opposed a move to the winter months adding to pressure on FIFA which has a task force working on the dates. No decision is expected before February next year however.
The EPFL, which represents 31 leagues, including England, Spain, and Germany, said a winter World Cup would damage European leagues.
Association chairman Frederic Thiriez said "The EPFL considers that any re-scheduling of the World Cup would be damaging the domestic competitions and leagues' business and sporting interests."
ECA clubs may press for a May World Cup in 2022 when the FIFA task force meets again in November, according to British media reports.
The ECA discussed a possible May World Cup at a meeting in London this month, the reports said.
Because Qatar's temperatures regularly rise above 40 degrees Celsius (104 Fahrenheit) in summer months, FIFA president Sepp Blatter has said the tournament should be held in November-December.
But that would mean splitting the European season as well as disrupt the Champions League.
Blatter has acknowledged that a winter World Cup would annoy European clubs, who employed about 75% of the players at this year's tournament.
"We cannot play the World Cup in summer," Blatter told the France Info radio station again on Monday. "The date which is the most convenient is the end of the year."
Blatter acknowledged the clubs' concerns but said "The World Cup is too important."