Is it permissible for an employee to take materials from warehouses belonging to his employer, in excess of the inventory and with the knowledge and approval of the officials? Is this considered exploitation, and what should he do if it is not permissible for him to do so?

If the materials are of considerable financial value, it is absolutely forbidden for the inspector to take them, unless the law regulating the inventory process permits it and there is no suspicion of bribery or favoritism. Otherwise, taking them falls under the threat mentioned in the Hadith (definition): "Indeed, there are men who delve into the wealth of Allah without right, and for them is the Fire on the Day of Resurrection," and the Hadith: "Allah has cursed the briber, the bribed, and the one who facilitates it." Therefore, he must return the materials or their value to the state.