Ahmad was in Paris for the FIFA Congress and start of the Women's World Cup when he was picked up in the morning at a luxury hotel for what FIFA President Gianni Infantino described as "interrogations."
FIFA stressed that Ahmad was being questioned "in relation to allegations related to his mandate" as president of the African Football Confederation, rather than duties associated with the governing body.
CAF presidential adviser Hedi Hamel said in a text message late Thursday that Ahmad had been released and was back at a Paris hotel. Ahmad could not be reached by telephone.
FIFA earlier confirmed Ahmad, who is from Madagascar, is already embroiled of its own investigation, which follows allegations of wrongdoing in recent months.
"FIFA is asking the French authorities for any information that might be relevant to investigations taking place within its ethics committee," FIFA said in a statement.
After playing football in the shadow of the Eiffel Tower, Infantino said the Ahmad being embroiled in a case made him "sad."
"He was brought to be interrogated. We have to wait for the outcome," Infantino said in the early evening. "Of course, I said it yesterday very clearly we have cleaned up FIFA. This was the first step. We need to lead by example. If other steps are needed, we will know it when we have more information, which we don't have yet. And we hope, of course, that everything will be fine."
Ahmad has been accused by former CAF secretary general Amr Fahmy of bribing heads of soccer associations and misusing hundreds of thousands of dollars.
French authorities haven't disclosed details of the investigation.
"If anyone thinks he can enrich himself with illicit illegal activities around football, he has no place in football," Infantino said. "This is very, very clear and we will be there for Africa, as we are there for all other continents, and we will make sure that we can help in a very efficient way."
Infantino vaguely touched on problems in CAF in an address to the continent's soccer associations on Tuesday.
"I know there is a certain amount of turbulence," Infantino said. "I would urge you at this difficult point to urge you to always keep your cool and keep the spirit of solidarity. ... Try to find solutions, not problems."
Since Infantino was elected FIFA president in 2016, four continental soccer organizations each lost elected FIFA Council members amid allegations of corruption or financial misjudgments.
FIFA senior vice president David Chung of Papua New Guinea was banned for 6½ years, Kwesi Nyantakyi of Ghana was banned for life, Sheikh Ahmad of Kuwait withdrew his re-election candidacy when implicated in bribing voters, and Reinhard Grindel of Germany resigned.
"Where there are human beings — there are the strengths of human beings, but also the weaknesses of human beings," Infantino said. "So we need to look into our structures and we need to see how we can act.
"But, in any case, whatever the statutory legal situation is, we will be there. We will intervene."
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