Infantino and Trump have formed a close bond in recent years, with the U.S. one of the co-hosts for next year's men's World Cup.
Infantino even presented Trump with the inaugural FIFA peace prize at last Friday's World Cup draw in Washington, D.C.
- New FIFA peace prize awarded to U.S. President Donald Trump
FairSquare, a group which seeks to promote greater accountability in sport, has written a letter of complaint to FIFA's ethics committee alleging comments made by Infantino about Trump -- and the process followed to award him with the peace prize -- were in breach of FIFA rules.
In October, Infantino used his Instagram account to say Trump "definitely deserves" the Nobel Peace Prize.
After a video about Trump was played out at the draw prior to him receiving the FIFA peace prize, Infantino remarked: "This is what we want from a leader ... you definitely deserve the first FIFA Peace Prize for your action for what you have obtained in your way but you obtained it in an incredible way and you can always count, Mr. President, on my support."
Infantino said in a November interview at the American Business Forum in Miami that "we should all support what [Trump] is doing [in the U.S.] because I think it's looking pretty good."
FairSquare's letter, first reported by The Athletic and seen by the Press Association, also referenced an Instagram post from Infantino on Jan. 20, the day of Trump's inauguration.
"Together we will make not only America great again, but also the entire world," Infantino said at the conclusion of a video message.
FairSquare also called on the FIFA ethics committee to investigate how Trump came to be awarded the FIFA peace prize.
"The award of a prize of this nature to a sitting political leader is in and of itself a clear breach of FIFA's duty of neutrality," FairSquare's letter stated.
FairSquare said that based on FIFA's own statutes, the decision to introduce such a prize should have been taken by the FIFA Council.
"The FIFA president does not have the authority to unilaterally dictate the organisation's mission, strategic direction, policies and values," the letter added.
"This complaint is about a lot more than Infantino's support for President Donald Trump's political agenda," said Nicholas McGeehan, FairSquare's programme director.
"More broadly this is about how FIFA's absurd governance structure has allowed Gianni Infantino to openly flout the organisation's rules and act in ways that are both dangerous and directly contrary to the interests of the world's most popular sport."
FIFA has been approached by PA for comment.
Information from PA was used in this report.
