use SAVEPOINT function

Greetings,

I'd like to know is it possible to use "SAVEPOINT" in a function? In the
following example, I got an error when calling this function:

CREATE OR REPLACE function test() returns trigger as $test$
BEGIN
SAVEPOINT savepoint1;
... ...
COMMIT;
RETURN NEW;

EXCEPTION
when RAISE_EXCEPTION THEN
ROLLBACK TO SAVEPOINT savepoint1;

END;
$test$ language plpgsql;

Thanks a lot,
Emi