The Italy forward angered activists with his comments about gay players in the Azzurri, and has come under further criticism despite making an apology
Cassano said he hoped he had no gay team-mates, and Hysen, who is the half-brother of Anton Hysen, one of football's first openly gay footballers, is adamant that a man of the AC Milan striker's standing should not be making such statements.
"It is difficult to know how to deal with things like this," he told Swedish paper Aftonbladet. "Everyone must remember that this was just one person saying something like that, but the Italian Football Federation must look into it."
"I don't understand how a role model such as Antonio Cassano can say something like that. It is sad.
"Someone who is playing at that level cannot say something like that."
This is not the first time the Azzurri camp has been engulfed in criticism over the issue; coach Cesare Prandelli had earlier called for gay players to come out, but Udinese striker Antonio Di Natale claimed that such a thing would be almost impossible.
Cassano has since apologised for his comments and stated that he is not homophobic.