Sinha said India stood to "lose and not gain" by becoming a member of the 48-nation grouping and alleged that people sitting in the government were "misguiding it every day."
"India which has shown so much keenness and desperation in getting NSG membership, it is not required at all. We are comfortable outside NSG. If we become members of NSG, we will have more loss. There will be no gains for us.
His comments came after India failed to make the cut despite intense lobbying, including a meeting between Prime Minister Narendra Modi and Chinese President Xi Jinping on the sidelines of Shanghai Cooperation Organisation (SCO) summit in Tashkent as some countries backed by Beijing blocked New Delhi's entry into the NSG on the ground that it was not a signatory to the Nuclear Non-Proliferation Treaty (NPT).
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Sinha, who was External Affairs minister in the Atal Bihari Vajpayee government, has spoken out against various aspects of Modi government's foriegn policy, especially its handling of relations with Pakistan.
Gloating over the Modi government's failure, Congress termed the vigorous push for NSG membership as "event management" and accused it of "embarrassing" the nation with its "misplaced euphoria".
"There was no reason for our government to file the application. It was ill-advised -- the desperation, which the Prime Minister showed and also the prematured claims, which he made when he went to Switzerland and Mexico as if everybody is endorsing us," former Union Minister and senior Congress spokesperson Anand Sharma said.
"There were huge celebrations that Switzerland and various other countries are supporting us. But eight to nine countries opposed us including Switzerland," he said.