Resignation acceptance letter only instead of relieving letter?

I worked as permanent employee in a public sector bank. As per terms of appointment i served 3 months notice period. At the last day of notice period, i got letter from controlling office stating that competent authority has accepted resignation from banks service w e.f. 16/09/2017 on close of business. On asking for relieving letter they said this is sufficient. Will this be sufficient for further employment in govt sector jobs on do i need proper relieving certificate. What are my options to get the relieving letter from previous employer.

A resignation acceptance letter could be sufficient if it states the fact of relieving too. Some organisations issue composite order on the last date of notice. If you can share the material contents of the letter , more definite opinion could be offered. But, since the bank is not agreeing to give you a separate relieving order, you can and must insist on a 'No Dues Certificate'. NDC certificate + Resignation Acceptance Letter suffices for any future employment.

Dear Sir,
Please find the exact content in attachment

Every PSU bank has clear cut policy regarding acceptance of resignation.
Read it from bank website or from HR department.
Since your resignation has been accepted, follow it up with a letter from your side confirming handing over taking over of duties, surrender of accommodation, bank property etc and ask for acknowledgement.
Insist on no dues certificate.
I am sure your website or HR department portal on bank website would give clear guidelines.