The organisers insisted they always planned to ring-fence tickets at set prices to follow your own team.
But the announcement comes ahead of Friday’s tournament draw in Washington DC that President Trump plans to attend.
Fans will have to wait until Saturday to know exactly where and when their teams will be playing in next summer’s tournament.
Variable pricing – fluctuating based on demand – has never been used at a World Cup before, raising concerns about affordability being mostly played in the United States.
England and Scotland fans have been sharing images in recent days of ticket website images highlighting cost worries.
But world football’s governing body said in a statement to Sky News: “FIFA can confirm ringfenced allocations are being set aside for specific fan categories, as has been the case at previous FIFA World Cups. These allocations will be set at a fixed price for the duration of the next ticket sales phase.
“The ringfenced allocations include tickets reserved for supporters of the Participating Member Associations (PMAs), who will be allocated 8% of the tickets for each match in which they take part, including all conditional knockout stage matches.”
FIFA says the cheapest tickets are from $60 (£45) in the group stage. But the most expensive tickets for the final are $6,730 (£5,094).
There will also be a sales window after the draw from 11 December to 13 January when ticket applications will be based on a fixed price for those buying in the random selection draw.
It is the biggest World Cup with 104 matches after the event was expanded from 32 to 48 teams. There are also three host nations for the first time – with Canada and Mexico the junior partners.
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FIFA defended using fluctuating pricing.
“The pricing model adopted for FIFA World Cup 26 reflects the existing market practice for major entertainment and sporting events within our hosts on a daily basis, soccer included,” FIFA’s statement continued.
“This is also a reflection of the treatment of the secondary market for tickets, which has a distinct legal treatment than in many other parts of the world. We are focused on ensuring fair access to our game for existing but also prospective fans.”
The statement addressed the concerns being raised about fans being priced out of attending.
FIFA said: “Stadium category maps do not reflect the number of tickets available in a given category but rather present default seating locations.
“FIFA resale fees are aligned with North American industry trends across various sports and entertainment sectors.”
Ireland, Northern Ireland and Wales could also still qualify.
