Opening of demat account / trading account frm outside india

Dear Knowledgeholder, I have a query regarding procedure for opening of a demat account in India from outside India in any Indian Bank. Please tell me whether it can be done online or does it need physical presence. Person needing demat account have an account in an nationalised bank too and he is Indian resident but currently residing out of India. Thanks a lot for your valueable suggestion(s) / comment(s) or idea(s) and for the time you took to reply my query. With Regards Dhiraj Kumar