temp table creation

What's wrong with this function? The syntax is supposed to be right,
isn't it?

Create function UsaTablaTemporal()
RETURNS integer
AS '
    BEGIN

 SELECT p.apellidos, p.nombres, u.username
        INTO TEMP TABLE mitabla
        FROM persona p, usuario u
        WHERE p.idpersona = u.idusuario
          AND p.idpersona = 3278;

        RETURN 1;

    END;'
LANGUAGE 'plpgsql';

If I run:
select usatablatemporal();

I get the message:
ERROR:  parser: parse error at or near "temp"

Thanx