Real Madrid say they have supplied "all available evidence" to UEFA as the governing body investigates allegations of racism made by their forward Vinicius Junior.
The Brazilian says he reported racial abuse by a Benfica player to referee Francois Letexier during Tuesday's Champions League knockout round play-off tie in Lisbon.
Real said this player was Benfica winger Gianluca Prestianni.
UEFA said on Wednesday it had opened a disciplinary investigation into events at the match, and Real have now issued an update.
"Real Madrid CF announces that it has today provided UEFA with all available evidence regarding the incidents that occurred (on) Tuesday, February 17, during the Champions League match that our team played in Lisbon against SL Benfica," a club statement read.
"Our club has actively co-operated with the investigation opened by UEFA following the unacceptable episodes of racism experienced during that match.
"Real Madrid is grateful for the unanimous support and affection that our player Vinicius Jr. has received from all sectors of the global football community.
"Real Madrid will continue working, in collaboration with all institutions, to eradicate racism, violence and hatred in sport and in society."
After the game, Vinicius posted in Portuguese on his Instagram story: "Racists are, above all, cowards. They need to put their shirts in their mouths to demonstrate how weak they are.
"But, they have protection from others who, theoretically, have the obligation to punish. Nothing that happened today is new in my life and my family's.
"I received a yellow card for celebrating a goal. Still not understanding why. On the other side, just a poorly executed protocol that served no purpose.
"I don’t like to appear in situations like this, even more so after a great victory and when the headlines have to be about Real Madrid, but it’s necessary."
In a statement in Portuguese on Instagram, shared by Benfica on social media, Prestianni denied making racist comments.
