Probably Guldimann from Switzerland. His term was 1999 to 2004, so it could have been him. He represented US interests in Iran so he would have seen the sort of things that are talked about here. But it could have been someone else. Guldimann fits and his dates fit.
World Jewish Congress: Nazi train treasures must go to rightful owners (Reuters)
from the article: The message is clear: Israel must not strike Iran