* Nuclear export body meets in Buenos Aires on June 26-27
* Relationship with non-member India among issues to be discussed
* U.S. and Britain have argued for India membership
* But China and others believed to have doubts - diplomats
By Fredrik Dahl
VIENNA, June 24 (Reuters) - An influential world body that controls nuclear exports will address the sensitive issue of closer ties with India - which is outside the nuclear Non-Proliferation Treaty - at an annual meeting this week, a draft agenda obtained by Reuters showed.
The United States, Britain and others have argued that nuclear-armed India should join the secretive 48-nation Nuclear Suppliers Group - established in 1975 to ensure that civilian atomic trade is not diverted for military purposes.
But other NSG states have voiced doubt about accepting a country that built up a nuclear arsenal outside a 189-nation treaty set up four decades ago to prevent states from acquiring such weapons of mass destruction.
Days ahead of the June 26-27 NSG meeting in Buenos Aires, India said it was ratifying an agreement, a so-called Additional Protocol, with the International Atomic Energy Agency to expand oversight over its civilian nuclear programme.
The United States said this marked another "important step in bringing India into the international non-proliferation mainstream". But some critics questioned the step's significance, as it would not affect India's nuclear weapons programme and sensitive atomic fuel activities.
They said the Indian agreement was a much weaker version of a deal most other IAEA members have, giving the U.N. watchdog wide inspection powers to make sure there are no covert nuclear activities in a country.
"India's version of the Additional Protocol is a paper tiger," said Daryl Kimball of the U.S.-based Arms Control Association, a research and advocacy group.
A diplomatic source said he did not expect any decision on the membership issue at the NSG plenary meeting in Argentina's capital, suggesting it would take more time.
The diplomatic tussle centres on whether the emerging power should be allowed into a key forum deciding rules for civilian nuclear trade, even though it never joined the 1970 Non-Proliferation Treaty (NPT), under which it would have to give up its nuclear weapons.
The agenda for the meeting on Thursday and Friday said members would be "invited to a general discussion on the NSG's relationship with India", without giving details on this point.
The NSG's outgoing chair before Argentina takes over, the Czech Republic, is to report on "consultations with India regarding dialogue and cooperation" with member states.
India - Asia's third-largest economy - would need the support of all NSG states to join the cartel that has a pivotal role in countering nuclear threats and proliferation.
If India eventually were to become a member, it would boost its standing as an atomic power. It would be the only member of the suppliers group that has not signed up to the NPT.
Supporters say it is better if the country is inside than outside the NSG as it is already an advanced nuclear energy power and will in future become a significant exporter as well.
Those who are sceptical argue it could erode the credibility of the NPT, which is a cornerstone of global nuclear disarmament efforts.
Diplomats have said that China and some others have been doubtful. Beijing's reservations are believed to be influenced by its ties to its ally Pakistan, India's rival, which has also tested atomic bombs and is also outside the NPT, analysts say.
To receive civilian nuclear exports, nations that are not one of the five officially recognised nuclear arms states - those that had known arsenals before the NPT was hatched - must usually place their nuclear activities under IAEA safeguards.
When the United States sealed a nuclear supply deal with India in 2008 that China and others found questionable because Delhi is outside the NPT, Washington won an NSG waiver from that rule after long and contentious negotiations in Vienna. (Editing by Mark Heinrich)