The European Union's delegation in Sudan has announced that it will monitor the voter registration process. I can't find anything on their website yet, so for now here is a secondary source: http://www.google.com/hostednews/afp/article/ALeqM5iRTEwRWCruVXK-sJuavmimTrl9bQ?docId=CNG.c475d315dd94dc3d274371ac27c49236.6e1
It is somewhat unusual to have international observers at voter registration. Registration usually takes longer than voting and counting ballots, and may take place in more diffuse ways and locations, so cost becomes a factor.
The Carter Center also has monitors in Sudan to register the voter registration process: http://www.cartercenter.org/countries/sudan-peace.html