Casillas and Raul became club legends during a combined 43 years in the Spanish capital, helping Los Blancos to win seven La Liga titles between them.
Raul would leave the Bernabeu in 2010, moving to Schalke following an injury-plagued final season with Madrid, having scored more than 300 goals for the Spanish giants.
Goalkeeper Casillas meanwhile fell foul of Jose Mourinho and was forced out of the Spanish capital by the Portuguese manager after turning out more than 700 times for the club.
But despite their legendary status among many fans and observes, a secret recording from a 2006 conversation has emerged in which Perez blasted the duo.
The conversation took place six months after he had resigned from his first spell as president amid criticism that he had focused too much on brand appeal rather than footballing success.
“What happens is that they [the fans] adore him, they love him, they talk to him. I don’t know why they defend him so much.
“Well, it’s one of the great frauds, the second is Raul. The two great Real Madrid frauds are Raul first and Casillas second.”
Perez then turned his anger towards Raul, who he accused of “destroying” the club, blaming him for his departure as president.
“[Zinedine] Zidane’s a great guy. And [David] Beckham and Ronaldo. … But then there are the others that think that … let’s see. Raul is a bad person,” Perez said.
“He thinks Madrid is his and he uses everything there is in Madrid, developing everything for his own benefit. Him and his agent. They are to blame for Madrid not doing well.
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“Look, I left, among other reasons, because of him. He is a negative guy, he is destroying Madrid.”
The publication of the recording will not only cause embarrassment because of Raul and Casillas’ club legend statuses.
The former is also currently the manager of Real Madrid Castilla, the club’s reserve side, and was linked with taking over from Zinedine Zidane before Carlo Ancelotti’s appointment.
Perez fired back in a statement, claiming that the recording has only been published to discredit him in the face of the European Super League scandal.
“Given the news broadcast in El Confidencial, in which phrases attributed to me are reported, I think it is necessary to clarify,” the statement read.
“The reproduced phrases are pronounced in conversations clandestinely recorded by Mr. Jose Antonio Abellan, who has been trying to sell them for many years without success.
“It is surprising now that, despite the time that has elapsed, the newspaper El Confidencial reports them today.
“They are single phrases of conversations taken from the broad context in which they occur.
“For them to be reproduced now, after so many years have passed since those conversations took place, is I understand due to my participation as one of the promoters of the Super League.
“I have put the matter in the hands of my lawyers who are studying the possible actions to take.”