private functions in a interface decleration

[bleak26]

When i declare a function private
in my interface decleration i recive the following error.

Fatal error: Access type for interface method dbwrapper::sanitise() must be omitted

Can any one tell me why?

Once again thankyou

interface dbwrapper {
public function connect_to_db($db_purpose_type);
public function set_query($query);
public function execute_query();
public function result_object();
public function prepare();
public function bind();
private function sanitise();
}

class mysqli_wrapper implements dbwrapper{
private function sanitise(){

}
}

[perl_diver]

is this perl?

[bleak26]

sorry guys ,it was late when i posted. please move this to the php forum.