The senior Congress leader said Advani's consent came after Singh explained the deal to him along with former Prime Minister Atal Behari Vajpayee and former National Security Adviser Brajesh Mishra in December, 2007.

Vajpayee and Mishra agreed fast that the deal is in the national interest as they were aware of the foreign policy, Sibal told Karan Thapar's programme Devil's Advocate.

Advani also told the Prime Minister that ‘we are now in a position to support the deal’ and that Singh should send a letter which will be responded to, Sibal said.

When the Prime Minister wrote the letter, Advani replied saying that he is not able to deliver the promise he had made to him as ‘senior party leaders are opposed to it’, Sibal said.

The Science and Technology Minister said former External Affairs Minister Jaswant Singh too was happy with the deal when NSA M K Narayanan, Foreign Secretary Shivshankar Menon and Atomic Energy Commission chief Anil Kakodkar met him.