Uefa says it has had no reply to a request for a special meeting with Fifa to discuss the plans.
Uefa released a statement on Wednesday highlighting its concerns about the proposal.
Among those, it says there are four key “dangers” in the plans – the dilution in the “value” and “mystique” of the World Cup, the erosion of opportunities for weaker national teams, the impact on players, and the risk for the future of women’s tournaments if they lose their exclusive slots.
In a statement, Uefa added: “These are just some of the serious concerns that the Fifa proposal provokes at first glance and they cannot be dispelled simply with unsubstantiated promotional slogans on the supposed benefits of a thicker calendar for final tournaments.
“In this phase, the respect for a consultation process with the stakeholders – which should be unbiased – would suggest abstaining from promotional campaigns of unilaterally predetermined concepts that nobody has been given the possibility to see in detail and which have wide-ranging, often unexpected, effects.”
On Monday, Fifa said it was opening a new phase in the consultation process by hosting a virtual summit, open to all national associations, on 30 September.
Fifa president Gianni Infantino wants to put the proposals to a vote before the end of 2021.
His Uefa counterpart Aleksander Ceferin has previously rejected the idea of holding the World Cup every two years, saying it would “dilute” the tournament.
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