SQL & PL/SQL

Dear all,
I have a package that has procedures related to other.
I want to grant some users execute on some of those procedures, and others execute on other
procedures.
Say
create package holiday_pkg as
procedure ask_holiday(emp_no in number, period in number, start_date in date);
procedure approve_holiday(holiday_seq in number);
end;

I want user_employee to have the privilege to execute ask_holiday and not to execute
approve_holiday. user_manager to have the privilege to execute both procedures.

Would someone tell me the best way to do that?
Or I have to split the procedures into two packages, I do not want it this way.

Thanks.