Oracle error creating IDENTITY column

Question

I have a CREATE TABLE statement which works fine.

However, when the following is added (as the first column in the table):

CREATE TABLE my_table
(
    id NUMBER GENERATED ALWAYS AS IDENTITY,

This error is thrown:

Error report:
SQL Error: ORA-02000: missing ( keyword
02000. 00000 -  "missing %s keyword"

What is wrong?

Thanks