'"The circular, signed by the Acting Director, Banking and Payments System Department, Mr Giaus Emokpae, said that the exemption was because Nigeria was  signatory to several treaties"

If Nigeria where signatory to several treaties with countries having exempted embassies, diplomatic missions, multilateral and aid donor agencies from penalties and charges on daily cash withdrawal and deposit limits, and as well exempted their citizens too, why can't Sanusi do away with such classified slavery from Nigeria to Nigerians only?

Bullshit. Be careful, Mallam. Nigerians are not animals they are human beings, any law that is  not good for international communities will not be good for them as well.