The nature of the deposits made by the clients in the banks of the Islamic Republic of Iran is such that the clients deposit their money with the bank on short or long term basis. The bank acts as an agent of the client using his savings in [business] transactions. In this case the transactions conducted by the bank are interest-free. The interest earned by the bank through these transactions belongs to the depositor but the bank receives a part of the interest as haq al-wikalah [i.e. the right of agency].
As for the interests given by banks of other countries, it depends on the nature of the contracts concluded between the client (depositor) and the bank.
 - Students Manual of Islamic Laws according to the views of ten grand jurists, pg. 269, Bank rules, No.1; Answers to Religious Queries, pg. 505, question 1926.