trigger for granting permission to select a table as soon it is created

HI
I am using postgersql and i am newbie,

i want to grant select permission to a group on table that will be created by me in future.
so i used trigger and a function

CREATE FUNCTION permitselect () RETURNS opaque AS 'DECLARE BEGIN GRANT SELECT ON  NEW to GROUP wp; RETURN NEW;  END; ' LANGUAGE 'plpgsql';

and trigger as
CREATE TRIGGER permit_select
               AFTER INSERT OR UPDATE
                ON queries FOR EACH ROW
                EXECUTE PROCEDURE permitselect();

queries is table where meta data of tables created by me is stored. so new table created will be listed in table queries.

but on execution it  gives error:
NEW used in non-rule query
Error occurred while executing PL/pgSQL function permit

Can any body help me how i can write a trigger for granting permission to select a table as soon it is created

thanks in advance
santosh dwivedi