insufficient privilege to create temp table from stored proc

I am trying to create a temporary table, which works fine in SQL-PLUS, but gives me an insufficient privilege error when run as below in a stored procedure.
Any idea what privilege I'm missing. I've been going round and round int he help for about half an hour.

Thanks,

Jon

PROCEDURE create_temp_tables IS
BEGIN
execute immediate 'create GLOBAL TEMPORARY table temp_client  (id decimal(15), sin int, dob date, sex char(1), fil int,role char(2),age int,realdob int)';
END; Received on Mon Feb 11 2002 - 10:10:45 CST