This is another scam within a scam. People who get scammed are approached by other (or the same?) scammers claiming they are officials trying to catch the scammers and get back the money for the victims.
However, those who claim to be officials, local or international, are scammers themselves and are often able to scam the victim for more money than the origial scam was worth.
Here is an example of a man in India who was scammed by a person claiming to be from the non-existent United Nations Intelligence Bureau.