UEFA, Europe’s main soccer body, said on Thursday its members would boycott the men’s and women’s World Cup unless FIFA abandons a controversial plan to sell stakes in in the tournament to private investors.

A boycott of one of the world’s top sporting competitions would mark an unprecedented step for European nations. It also threatens to imperil a proposal unveiled by FIFA this week to create a company to handle all commercial rights to its tournaments, including the marquee World Cup.

The dispute comes ahead of the 2030 FIFA World Cup, which will mark the tournament’s centenary, celebrating 100 years since the inaugural edition in Uruguay in 1930. The event will be staged mainly in Spain, Portugal and Morocco, with centenary matches in Uruguay, Argentina and Paraguay.

Under the proposal, FIFA would also sell minority stakes in that newly-created companies to private investors, including a firm run by Joshua Kushner, the brother of President Trump’s son-in-law Jared Kusnher. The plan to sell minority stakes sparked fury across European soccer bodies.

“Some things are simply too important to sell. The FIFA World Cup belongs to football. It always will. And so long as Europe has a voice, it will never be for sale,” UEFA said in its statement.

England’s Football Association said: “We stand shoulder to shoulder with our European colleagues and fully support the collective view.”

Concacaf, football’s governing body for North America, Central America and the Caribbean, has called an emergency meeting of its 41 member associations on Thursday to discuss FIFA’s proposal. The confederation said it was “deeply concerned by the lack of due process” and stressed that decisions affecting the game must be guided by “good governance, robust processes and long-term stewardship.”

‘Football changes forever’

FIFA had defended its proposal, saying it would retain all decision making power across all its tournaments, while noting that its proposal involved only selling part of the commercial venture.

UEFA, which represents 55 member soccer associations across Europe, questioned that promise in its sharply-worded statement on Thursday.