Paul Buchanan, 36th Parallel Assessments Director said New Zealand was seen as a target because our security wasn't as robust as other countries up until recently.
"By coming here they get an equally good quality education, but they don't raise the attention of security authorities in the Northern Hemisphere," Buchanan told Newshub.
But Professor Kevin Clements from Otago University said most information on how to build WMDs can be found on the internet.
"If you were really interested in developing weapons of mass destruction, you wouldn't come to New Zealand," Clements said.
He expressed concerns that applicants from certain countries were being discriminated against.
INZ said the applicant's country of origin, their occupation and associations were among the factors it considers when making decisions about who to investigate.
Documents from the Immigration Profiling Branch revealed that officials look at the applicant's CV and background information, a list of all addresses around the world where the applicant has lived, PHD research proposal and why NZ has been chosen for their studies.