On Wednesday night, Infantino was given the "full support" of FIFA's management board in a statement despite being forced to abandon his plan to sell stakes in a company to run the World Cup to private investors.
The European governing body had initially threatened to boycott FIFA tournaments while the plans were in place and on Thursday reiterated that stance - while doubling down on their demands for Infantino to go.
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FIFPRO added to growing opposition to the president's position in a damning statement which slammed the "cover-up" surrounding the entire situation, and said it had noted FIFA's statement "with deep concern", also hitting out at the governing body's framework for allowing the plans to be hatched.
"No institution can restore confidence in a presidency that has itself dismantled the conditions upon which confidence depends," it added, as well as laying out a series of demands to FIFA including "legally-binding engagement" with footballers, voting rights on the FIFA council and reforms which would prohibit "any individual, ever again, to drive unilateral decisions through the game".
Also on Thursday, the Football Association formally announced its intention to withdraw support for Infantino's re-election as president, with a vote currently scheduled for March 2027.
UEFA was the first continental body to speak out against Infantino's plans and was the only one to threaten a total boycott of FIFA competitions - and in their first public comments since they were withdrawn, said there had been insufficient change to reverse their stance with Infantino remaining in post.
A statement read: "UEFA's associations were very clear about the conditions attached to the non-participation in FIFA competitions.
"First, the proposals to sell off the major competitions had to be withdrawn, and secondly, assurances have to be made that such attempts to disfigure the game in this way will never be made again.
"These conditions have not been met. In addition, UEFA made it abundantly clear in its statement on Saturday that it has lost confidence in Gianni Infantino's presidency. That position holds.
"Yesterday's [Wednesday] announcement that some people employed by the FIFA President (and whose careers depend on his favour) agree with him changes nothing."
The first test of UEFA's boycott will come at next month's FIFA U20 Women's World Cup, in which England will compete after naming their final training squad on Wednesday.
For the senior national teams, the boycott's next major test will come in October, when England, Scotland, Wales, Northern Ireland and the Republic of Ireland are scheduled to take part in the play-offs for qualification to the 2027 FIFA Women's World Cup.
Why Infantino is still in power
Infantino has shaken off calls to resign - for now - with the backing of the governing body's leaders, though he apologised for "mistakes" in his botched attempts to sell off a stake in the World Cup.
In a statement released after seven hours of crisis talks in Morocco on Wednesday, FIFA said its management board had reaffirmed their "full support" for Infantino - including secretary general Mattias Grafstrom, only days after he had labelled the World Cup plans "a sad and reproachable series of events". The pair were later seen laughing together watching a Women's AFCON game in Rabat.
Infantino had faced mounting calls to resign following the leak of previously undiscussed proposals, after it was revealed national associations had not been consulted and had been given a deadline barely a month away in mid-September and the promise of a £30.1m incentive to back them.
In a letter seen by Sky News sent to national associations and signed by Infantino and Grafstrom, the pair wrote that they "sincerely apologised for the errors" in the plans which were eventually withdrawn on August 1 following days of criticism from across world football.
A second statement released publicly through FIFA.com hit back at those critics, threatening that FIFA would "no longer tolerate any attacks on its integrity, good governance and due process and will take all necessary measures to protect and safeguard its name and reputation".
FIFA said it had "not been the intention… for member associations to feel excluded from the process" and admitted they should have been "handled differently" while further acknowledging "errors were also made after the proposal was leaked to media."
The governing body also promised a review would be conducted into the fiasco and a report into its findings presented at the next FIFA Council, comprising 37 national representatives from around world football.
Infantino and FIFA's reputation had taken increasing hits from inside and outside of its own walls over the plans with Arsene Wenger, its chief of global football development, distancing himself publicly while Infantino's personal senior advisor Carlos Cordeiro quit his role on July 31, labelling them a "bad deal" and "irresponsible".
Timeline: How FIFA's World Cup private investment plan imploded
July 28: FIFA announces its "FIFA forward Enterprise" investment plan, proposing to spin off the commercial rights to competitions, including the World Cup, into a new company.
July 28: UEFA launches a fierce public attack, accusing FIFA of rushing through a transformative proposal with little consultation.
July 30: UEFA's 55 member associations vote to boycott World Cup if plans go ahead.
July 31: Infantino's adviser Carlos Cordeiro resigns amidst the controversy.
July 31: UK Prime Minister Andy Burnham says Infantino is the "wrong man" to lead FIFA.
August 1: FIFA abandons the investment plan after only a few days of intense opposition. Infantino withdraws the proposal before it reaches a formal vote.
August 1: UEFA releases a statement in which it says it has lost confidence in Infantino's leadership of FIFA.
August 1: Spanish league boss Javier Tebas says Infantino "must not continue at the helm of FIFA".
August 3: Wales becomes the first Football Association to officially withdraw support for Infantino's re-election as FIFA president.
August 3: UEFA reportedly threatens legal action and instructs lawyers to preserve FIFA documents and communications relating to the proposal.
August 3: English Football Association set to write to Infantino withdrawing its previous support.
August 5: Luis Figo became the first legendary former player to call for Infantino's resignation.
August 5: Crisis meeting held in Morocco and FIFA reaffirms "full support" for Infantino.
August 6: UEFA boycott still stands with Infantino remaining in position.
