I mostly agree with the above by Eric but it's largely dependent on your career goal.
if you goal is to start as a researcher/scientist in international organizations, a BA in Economics is a great place to start but I strongly recommend you to get a PHD (i.e. international economics/finance) after that. Most of the international organizations requires researchers to have advanced degree.
If you'd like to start as an assistant/coordinator, finance/other relevant majors would be good depending on which fields you are more interested in (international orgs like Worldbank have a lot of different units focusing on different fields/industries). Some NGO intern experience would also be helpful.