FIFA's plans for a biennial World Cup would have a "profoundly detrimental" impact on the women's game and fundamentally alter its development, Europe's top women's leagues and European governing body UEFA said on Monday.
In a joint statement , the organisations criticised the consultation process FIFA employed while conducting a feasibility study into holding the men's and women's World Cup on a biennial basis.
The organisations also expressed concerns about the tournament adding to an already congested international calendar, hampering the visibility of women's soccer and resulting in players being overworked.
"The fast-paced nature of the (so far) very selective consultation process and all-but agreed proposals have not allowed a careful reflection on what is in the best interests of... women's football or adequately assessed the possible irreversible consequences such a change might entail," the statement said.
"To be clear, this is not in any way about Europe defending its position, nor a question of national team versus club football.
"Our reservations centre on our desire for a balanced and inclusive global development that gives women and girls the best conditions to play the most beloved game at all levels and in every society."
The statement was co-signed by the European Club Association (ECA) and women's leagues from England, Germany, Italy, Finland, Romania, Sweden, Switzerland and the Netherlands.
The ECA, which represents 234 European clubs, said last month a biennial World Cup would lead to a "direct and destructive impact on the club game" while UEFA urged FIFA to engage in "genuine consultation" over reforming the calendar.