Manchester United chief executive David Gill has criticised FIFA following mixed messages about the scheduling of the 2022 World Cup in Qatar.
The European Club Association, representing 197 clubs across the continent, have underlined their opposition to playing the tournament during the winter - even though summer temperatures could reach 50 degrees Celsius in the desert heat.
A winter World Cup would mean a complete restructuring of the European calendar, and ECA general secretary Michele Centenaro said all clubs were opposed to "the disruption of the traditional domestic football season''.
FIFA president Sepp Blatter last month said he expected the 2022 finals to be played in winter, but he has since revised that stance and given a strong hint that the tournament will be held in the summer.
"It has not been dealt with correctly,'' said Gill. "There has been concern obviously in the way it has manifested itself. That is not just our view, it's the view of more than 100 clubs individually and collectively.
"This is a major thing that will have ramifications for club football for three years. For it to happen in that way was somewhat surprising. This is an issue that has not been dealt with correctly.''
Gill and others are also opposed to releasing players for two major competitions in the same season - notably next year when Euro 2012 and the London Olympics are separated by less than a month.
"A player who is in the Euro squad shouldn't be in the Olympics squad,'' said Gill. "Obviously we want to make a success of the Olympics and we are happy to release players but I think common sense will prevail.''
The ECA have warned that FIFA must pay more attention to their demands or risk conflict. Calling for a greater role in the decision-making process of the international match calendar was Sandro Rosell, the president of Spanish champions Barcelona and an ECA vice-president.
"I wouldn't say we are at war, the clubs are very patient, but we have our limits,'' Rosell told a press conference after the two-day ECA general assembly in Geneva.
"We hope UEFA and FIFA will hear what we have to say to them. We have no doubt they will listen to us and consider what we are asking for and that it is logical and fair.''
The clubs are angry that FIFA have added eight additional international fixtures to the match calendar from 2011-14, including this week's round of friendlies across Europe.
AC Milan operations director Umberto Gandini, the ECA vice-chairman, said the current schedule suited no-one.
"Tell me which national team manager or club manager is happy there is an international friendly tomorrow?'' Gandini said.
"All of a sudden we discover they (FIFA) can modify the calendar any time they like. If you are not heard you have to scream.''