The senior Congress leader said Advani's consent came after Dr Singh explained the agreement to him along with former prime minister Atal Bihari Vajpayee and former National Security Adviser Brajesh Mishra last December.

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

Advani told the prime minister that "we are now in a position to support the deal" and that Dr Singh should send a letter which would be responded to, Sibal said.

When the prime minister wrote the letter, Advani replied saying he was not able to deliver the promise he had made to Dr Singh 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 National Security Adviser M K Narayanan, Foreign Secretary Shiv Shankar Menon and Atomic Energy Commission Chairman Dr Anil Kakodkar met Jaswant Singh. "Gentlemen, I must compliment you on a job well done," Sibal quoted Jaswant Singh as saying.