The NSG which includes the United States, Russia, China, European Union countries and some others tries to ensure that nuclear exports are not diverted for military purposes. India already has enrichment and reprocessing capabilities and does not need more advanced equipment of this type. But the amended rules may still be seen as a blow for the Asian power, weapons proliferation expert Daryl Kimball said.
"The Indians are going to cry foul. They want to be able to say that they are under no nuclear technology trade restrictions and that they are a responsible nuclear power," said Kimball, director of the Washington-based Arms Control Association. "It is about prestige. It is not about any technical need."
India has so far not commented about the revised NSG guidelines, which have yet to be made public. To import nuclear goods, all nations except the five officially recognised atomic weapons states must usually place nuclear sites under safeguards of the International Atomic Energy Agency, the UN nuclear watchdog, NSG guidelines say. But when Washington sealed a nuclear supply accord with India in 2008, it won a unique exemption after contentious negotiations. India gained access to technology and fuel while it was allowed to continue its nuclear weapons programme.
The landmark civilian nuclear cooperation agreement ended India's atomic isolation following its 1974 nuclear test and could mean billions of dollars in business for US firms.
The revised NSG rules under discussion for years and adopted at a June 23-24 meeting in the Dutch town of Noordwijk do not apply to trade in reactors or in the uranium needed to fuel them, experts say.
But an added condition stipulates that only parties to the nuclear Non-Proliferation Treaty (NPT) can get uranium enrichment or spent fuel reprocessing equipment and technology.
This would bar all NPT outsiders India, Pakistan, Israel and North Korea from such items, which can have both civilian and military applications. India and Pakistan which have fought three wars and have tested nuclear arms have both refused to sign the 189-nation NPT, which is a cornerstone of global disarmament efforts.
"The new (NSG) guidelines include language saying transfers of enrichment and reprocessing technologies should be limited to NPT states and India doesn't qualify," proliferation expert Mark Hibbs of the Carnegie Endowment for International Peace said. "India has been trying to get that particular item out of the new guidelines and they failed," Hibbs said.