The NSG began a two-day meeting today in the Austrian capital to consider India's application and diplomatic sources said most countries appeared positive towards India's membership bid.
"It's an ongoing process but most countries appear positive," said the sources. India's membership is being strongly supported by the US.
However, reports from Vienna said that China was leading the opposition to India's membership. Turkey, New Zealand, Ireland, South Africa and Austria are said to be backing the Chinese stand.
China has been opposing India's entry into the elite grouping, consistently maintaining that only signatories of the Nuclear Non-Proliferation Treaty should be admitted to NSG. China wants NSG membership for Pakistan if NSG extends any exemption for India.
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In a letter, US Secretary of State John Kerry has made an appeal to NSG member states which are not supportive of India's membership bid, saying they should "agree not to block consensus on Indian admission" to the group when it again meets in Seoul later this month.
A joint statement issued after talks between Modi and Obama said the US called on NSG participating governments to support India's application when it comes up at the NSG Plenary later this month.
Modi on Monday had visited Switzerland, another member of the NSG which is known to have strong proliferation concerns, and it had announced support to India's candidature.
The NSG looks after critical issues relating to nuclear sector and its members are allowed to trade in and export nuclear technology. Membership of the grouping will help India significantly expand its atomic energy sector.