Mourinho said in his post-match interview that he had been told different things by Vinicius and Prestianni regarding the incident.
The Portuguese, who managed Real for 178 games between 2010 and 2013, pointed to their legendary striker Eusebio as proof that Benfica is not a racist club.
“The club reaffirms, clearly and unequivocally, its historical and unwavering commitment to defending the values of equality, respect and inclusion, which are in line with the core values of its foundation and have Eusebio as their greatest symbol,” Benfica said.
Mourinho’s and Benfica’s comments have been criticised by a number of people, including anti-discrimination charity Kick It Out.
Kick It Out chair Sanjay Bhandari said both the club and manager had “failed”.
“It’s a natural inclination to want to believe your player, but the reality is they didn’t hear it,” Bhandari told BBC Sport.
“There’s only two people who are in that conversation and two people who could have heard what was said.
“I think the better reaction from a club with Benfica’s fantastic stature would be to say we’re going to cooperate with the investigation.
“This is quite typical after these kinds of discriminatory events. The discrimination is one thing, the gaslighting is another.”
Fifa president Gianni Infantino said he was “shocked and saddened” by the incident and commended Letexier for activating the anti-racism protocol.
“There is absolutely no room for racism in our sport and in society – we need all the relevant stakeholders to take action and hold those responsible to account,” he added.
“I will always continue to reiterate: No to racism, no to any form of discrimination!”
