As per Income Tax circular 04/2009 dated 29th June, 2009 (Circular Link provided below), Form 15CA and 15CB Certificate under Section 195 of Income Tax is required to be submitted in cases where payments are made to a non-resident.
Residential status of a Company as defined u/s 6 (3) of Income Tax Act:
An Indian Company is always resident in India. A foreign company is resident in India only if, during the previous year, the control and management of its affairs are situated wholly in India. However, a foreign company is treated as non resident if, during the previous year, the control and management of its affairs are either wholly or partly situated out of India. The term “control and management” refers to “head and brain” which directs the affairs of policy, finance, disposal of profit and vital things concerning the management of a company. Usually control and management of a company’s affairs is situated at the place where meetings of its board of directors are held.
Deduction of tax at source from interest other than interest on securities u/s 194A of Income Tax Act in made in cases where payments are made to a resident:
Any person who is responsible of paying to a resident any income by way of interest, other than interest on securities, is required to deduct income-tax thereon at the rates in force.
However provisions of this section is not applicable where interest is credited or paid to any banking company, co-operative society engaged in banking business, public financial institutions, or notified institutions.
Based on above definitions, Indian Bank overseas branches becomes a resident and hence, whenever buyer’s credit interest payment is made to Indian bank overseas branches no TDS needs to be deducted and hence, form 15 CA and 15 CB is not required to be submitted.
For further details you can refer below articles
Buyer's Credit & Supplier's Credit 
In case of Buyer’s Credit, when are we required to submit form 15ca & 15cb. At the time of availing Buyer’s credit as payment to overseas party is indirectly being made on that date.As you already mentioned that the same is not required to be submitted for arrangements from overseas branches of Indian banks, so no liability arises to submit the same at time of repayment of principal & interest.
There are two payment we talking here.
1. Payment made to overseas suppliers: Form 15CA and Form 15CB required, irrespective if buyers credit is taken or not
2. Payment made to Indian Bank Overseas Branches on due date: Form 15CA and Form 15CB not required as per our interpretation as per details given above article.
Thanks for your reply, it means that form 15CA & 15CB is to be filed at the time when Buyer’s Credit is being availed for payment made to overseas party(exporter).
If we pay interest on Buyer’s Credit to State Bank of India Sydney Branch then no need to deduct any TDS or Form 15CA / CB
Sec 195 is applicable to Non Resident. As Indian Bank Overseas Branches are not a separate entity and As Indian Bank is resident and thus WHT, Form 15CA and Form 15CB is not applicable as per my interpretation.