UEFA president Aleksander Ceferin has "grave concerns" regarding FIFA plans to play the World Cup every two years.
World football's governing body is engaging in a PR offensive in order to pave the way for a biennial meeting of the world's best international sides.
Earlier this year, an overwhelming majority of FIFA members voted in favour of a feasibility study to look into staging the World Cup every second year.
In an interview with Friday's edition of L'Équipe, FIFA director of development Arsene Wenger spoke out in favour of the idea.
"The principle would be a grouping of qualifiers every year, and at the end of the season a major competition, World Cup or continental championship," the former Arsenal boss said.
Players signed up to FIFA's 'Legends' program like Javier Mascherano and Yaya Touré have also given their backing to the biennial proposal.
But Gianni Infantino's brainchild now finds stern opposition in the form of his opposite number at UEFA.
In a letter to Football Supporters Europe executive director Ronan Evain, Ceferin said, "UEFA and its national associations also have serious reservations and grave concerns surrounding reports of FIFA’s plans."
A number of African and Asian football federations have also backed FIFA's plan, but Ceferin does not share their enthusiasm.
"Considering the major impact this reform may have on the whole organisation of football,” Ceferin wrote, “there is widespread astonishment that FIFA appears to be launching a PR campaign to push its proposal whilst any such proposals haven’t been presented to confederations, national associations, leagues, clubs, players, coaches, clubs and all the football community.
“As one concrete example amongst so many, it is imperative to highlight the concerns shared across the footballing world regarding the impact a biennial FIFA World Cup would have on the international match calendar and, prominently in this context, on women’s football.”