block access to a function

[eluser]pam81[/eluser]
Hi all,
I'm making a typical class call user so there is a function register where you get the register's form wich could be access like www.mysyte.com/user/register

Code:

function register()
  {
  
   $this->load->view("header");
   $this->load->view("register");
   $this->load->view("footer");
  }

but there is another function add wich is call from the form to insert the user but I don't wanna somebody access like www.mysite.com/user/add because this only must be called from the register's form.

There is a way to prevent this kind of access?

Thanks in advance