The latest move in a power struggle between the two governing bodies came in the week after UEFA's European delegates were disappointed by what they perceived as a lack of clarity by FIFA president Infantino over the issues at a FIFA council meeting last week.
Infantino provided no documents about the $6 billion (US$4.2 billion) World Cup sell-off plan he launched and quickly dropped in July amid a fierce backlash led by Europe.
Among the 42 questions that UEFA are demanding an answer to are: Infantino's personal remuneration package, financial payments made to singer Marc Anthony, the handling of US striker Folarin Balogun's disciplinary case, business and political relationships involving Donald Trump and his family, and the operational independence of FIFA's judicial, electoral, and ethics committees.
UEFA have asked US federal courts to authorise subpoenas compelling the production of documents and sworn testimony about the abandoned investment plan called FIFA Forward Enterprise. FIFA lawyers have claimed UEFA is harassing Infantino.
The formal letter, signed by UEFA general secretary Theodore Theodoridis on behalf of European FIFA council members, stated Infantino's apology for his actions and subsequent explanation failed to address their core concerns.
"These explanations have not begun satisfactorily to address a number of fundamental questions raised by Council members. Others remain unanswered, and the information and documentation requested have not been (provided)," the letter said.
"The withdrawal of FFE, the recognition of mistakes, and the announcement of 'potential governance reforms' do not answer how the relevant decisions were taken or why the FIFA Council was not involved at the appropriate stage."
UEFA submitted 42 detailed questions to FIFA, demanding responses by Nov. 2, 16 days before the nomination deadline for the presidential election next March 18.
With the next FIFA council meeting scheduled for Dec 16 in Doha, after nominations close, UEFA insisted that answers cannot wait.
"These questions require answers now. They cannot be deferred until the next meeting of the FIFA Council, nor can future governance reforms substitute for scrutiny of decisions already taken and accountability for them," the letter stated.
