A man receiving money for the embassy on his account taking the difference after exchanging the money

Q: I work for an embassy where I am in charge of paying the salaries, and the rent of the premises. The country to which I belong sends checks in my name. I manage to cash these checks and convert the currency to that of the country where I live. As a result, I have made a large sum of money. I have not informed anyone of what I did, but I have paid all the salaries and the rent required. I have only done this once, after which I heard that it is inconsistent with the Shari`ah. Is this true? If so, should I return the money I took, or does it suffice for me to pay it to the poor? Otherwise, what should I do? Please answer me at my address, may Allah grant you success, and guide us to the right path, As-salamu `alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you!)

A: What you did is impermissible, and you must return the sum that you have taken to the country to which you belong. (Part No. 23; Page No. 434) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.