The eminent American scientist, however, emphasised that there were no concerns with regard to India misusing the agreement to become the proliferator of nuclear weapons.
"The real issue is - does it (the nuclear deal with India) have a negative impact on global efforts to stamp down proliferation. Some people in the US feel it does, others feel it will be strengthened if India comes in the fold," Neureiter told PTI in New Delhi.
"It is a complicated issue. Let us see what happens," said Neureiter, who is also Director of Centre for Science, Technology and Security Policy.
He said there were questions as to whether the US could have "closer relations with India without compromising the global efforts to stop proliferation."
Noting that he was not taking any view, the eminent American scientist said there are different views as to whether "it will do irreparable damage to the NPT or will in the long term strengthen NPT."
Asked whether there were apprehensions in the US that India could misuse the deal, Neureiter replied in the negative and said "I think the issue is whether an exception to India gives encouragement to Iran and to other countries."
He said "certainly, if there is exception to India, Pakistan will say they should have the same thing."
His views assume significance as Pakistan has already started demanding a nuclear deal with the US and other countries on the lines of Indo-American agreement. Pakistan President Pervez Musharraf has himself made this demand.
Queried whether opposition from some sections in America to the deal stemmed from concerns that India could be a proliferator, Neureiter said, "I have not sensed anything like that."
He underlined that India had no record of proliferation and "I don't think it will be in the future. So that is not the concern. The concern is the example whether it does damage the NPT regime."
Asked whether he felt it was necessary for India to put Fast Breeder Reactors in the civilian side as insisted by the Bush administration, he said, "There are some people who feel that way but the Indian side does not want to put it in. We have to see how discussions come out."On whether he believed the US Congress would endorse the deal without India putting the FBRs in the civilian side, Neureiter said he could not predict as "...there are different views. It remains to be seen how negotiations between the governments work out."