Fifa has accused Uefa of a "smear campaign against it and its leadership" in a challenge to litigation over president Gianni Infantino's scrapped plan to sell off stakes in the World Cup to private investors.
Last week European football's governing body filed legal papers in the US requesting disclosure of evidence and documents from Fifa as part of potential criminal claims in Switzerland.
In a dramatic escalation of the controversy, Uefa accused Infantino of "criminal mismanagement" and "a fraudulently off-market price promoted by [him] for his own benefit" over the now-shelved Fifa Forward Enterprise (FFE) scheme.
However, world governing body Fifa has now responded with court filings lodged in the US - and seen by the BBC - requesting that a court "oppose" the application by the end of the month.
Fifa claims Uefa's argument "suffers from a fundamental defect" and "legal deficiencies".
"Uefa seeks discovery in aid of a foreign criminal proceeding that does not exist and that Uefa admittedly lacks the authority to initiate. Despite that threshold problem, Uefa asks this court to authorise sweeping discovery about the FFE."
It said it had "made clear" that the creation of FFE was "only a proposal", adding that it could have only proceeded on the condition that the majority of member associations supported it and "the relevant approvals of the Fifa Council".
"Rather than participate in that democratic process, Uefa issued a press release - the beginning of a weeks-long smear campaign against Fifa and its leadership," it wrote in the court filing.
It also claimed that Uefa's "economic motivation" was to prevent smaller countries from having the "financial strength to compete with the European elite".
"If soccer is strengthened in the developing world, global competition increases, which ultimately reduces Uefa's market power and provides more competition for its flagship tournaments," Fifa said.
"By raising funds to allow some of Fifa's smaller member associations to better develop soccer, FFE would lead to more players from those nations choosing to represent their countries of origin and playing in their home leagues rather than playing abroad."
Uefa has declined to comment, although BBC Sport has been told insiders believe that if Fifa has nothing to hide, it should disclose the documents and speed up the legal process. It has led the rebellion against the Fifa president, who is facing calls to stand down from three confederations.
Uefa has also asked a court in New York to approve a legal document ordering testimony and documents from venture capitalist Joshua Kushner, the brother of US President Donald Trump's son-in-law, who was set to be the lead investor in FFE, and his company Thrive Eternal.
Thrive had held talks with Infantino about heading up a $4.2bn (£3.1bn) investment in 20% of a new Fifa commercial subsidiary, before the idea was abandoned days after it was revealed in July amid a huge backlash.
At the time, Fifa claimed FFE would have increased the funding distributed to each national association for the 2027-2030 cycle from £5.9m to £14.7m.
On Sunday, Kushner expressed regret over FFE, saying: "While we stand behind the motivations of FFE, we failed to appreciate the political dynamics of global football, and the lengths some would go to… had we known what this would devolve into, we would not have gotten involved."
Uefa has also asked for the disclosure of documents from American financier Greg Maffei, who was a key adviser on the deal.
While Uefa says neither Kushner nor Maffei are anticipated defendants in any legal proceedings, it claims the pair first discussed the FFE concept in July 2025 and that Infantino had "been discussing the underlying concept with Kushner for nearly a year before the terms sheet was ultimately signed".
Its lawyers also argue the World Cup was deliberately undervalued at about £15bn, which it says is "a figure that was neither the product of an open, competitive auction, nor tested by any independent valuer". Uefa claims Infantino failed to consult Fifa's hierarchy over the plan.
