The Evening Chronicle says sources in London claim Newcastle, Manchester United, Everton, Fulham, West Ham and Dutch champions Ajax have also expressed an interest in the England Under-21 international.
Palace boss Dougie Freedman said: "I don't think people will do that because they get very nervous with going to tribunals, there is not one set figure.
"Any responsible club would rather sit down face to face with our chairman and say 'Let's thrash a deal out', if they want the kid.
"I believe it will go that route, it's just a matter of seeing what happens.
"Nathaniel must have ideas where he is going to go because he has had a very good financial contract put on the table here.
"To turn that down he must have one or two options."