WHAT ARE THE POSSIBILITIES FOR GETTING A JOB IN EITHER OF THESE INSTITUTIONS..ANYONE WITH USEFUL INFORMATION SHOULD PLEASE FILL ME IN

It all depends on the qualification that you hold and the position that is being advertised. I think highly skilled professional with long years of working experience gets the offer better. Location of the applicant and the job in question is another aspect to be considered as the company or organization might want to employ someone that is closer to where the job is. These international organization survived based on financial contribution from member state therefore they can not afford to throw their money recruiting personnel from distance countries knowing fully well that it will involve plenty of money to fly you down to overseas.

They will prefer to employ one of the locals which might save cost.

However, I would like to recommend that you try to get to Abuja or Lagos ( Nigeria ) as this international office still have offices over here.

You can also use google to search their website and apply from there. best of luck