Depending on the context, it may be enough to say: "on this account", as it is the case in the source text.
As well explained in [http://www.proz.com/kudoz/english_to_serbian/finance_general...] every bank account has two parts - the first part is defining which bank is the one where the account is held - (in UK it's the "sort code", similar systems exist in other countries) - the final part is the account number given by the bank to its customer (here "partija").

From the point of view of the system of international bank transfers, "partija" as used in the bankers' jargon is a "sub-account" of the "account" the bank's account.

Nevertheless, in normal usage "bank account" by default refers only to the account number given to you by your bank, (although it's only a part of the IBAN), so a translation that would be understood correctly is here simply "account" (or "bank account" if it’s necessary to specify).

more about the format for bank account numbers on
[http://en.wikipedia.org/wiki/International_Bank_Account_Numb...]


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Note added at 23 hrs (2012-09-10 18:04:55 GMT)
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In banking you are more likely to have multiple accounts with the same bank, while sub-accounts are more likely to feature in accounting (you can breakdown an account in sub-accounts)