Maintaining that the Indo-US deal was delicately balanced, Foreign Secretary Shyam Saran has made it clear that substantial changes or revisions to it were unacceptable to India.

Saran said he hoped the new US legislation to implement it will be framed within already agreed parameters.

'We have preserved all our basic positions,' Saran said, debunking apprehensions of the deal damaging the credibility of India's nuclear deterrent.

• Coverage: The Indo-US nuclear tango

'I see no reason why there should be anxieties that we are always vulnerable to pressure,' he said in an interview to Karan Thapar on CNN-IBN to be telecast on Sunday.

'No, absolutely not. 100 per cent no,' he shot back on whether India's defence security has been sacrificed in finalising the agreement on civilian nuclear energy cooperation.

Saran, who recently returned after talks with the Bush Administration on implementation of the agreement, said, 'It is very important to remember that whatever we have agreed upon is the result of very, very difficult, very tough negotiations.

• Also See: The Bush Visit

'What we have at this point of time is an extremely carefully, delicately balanced understanding. Whatever legislation that is passed must remain within those parameters.'

Saran, who met several American lawmakers in Washington, said he expressed the 'strong hope' that 'revisions will not be made' and there will be 'no substantial changes'.

Contending that India has done 'rather well' in the negotiations, Saran said, 'We have preserved all our basic positions. We have preserved our basic interests.'

'Why are we always so worried about the screws being tightened on us... as if someone can come and turn the screws on us and we will just lie back and be screwed,' he said.

On concerns voiced by former prime minister Atal Bihari Vajpayee who demanded that India should try to get an all-time waiver from Washington as was the case with China, Saran said there was a 'factual problem' in this contention.

He said while China is a nuclear weapon state under the NPT, India wasn't.

Asked how India would respond if China and Pakistan carried out nuclear tests, Saran said under the agreement, India's decision on a moratorium on further testing remains but there was no mention of any 'permanent ban'.

He said India had taken a very conscious decision of undertaking nuclear tests in 1998 on the ground that it was important to take the step despite knowing what would happen.

'In the future, it will be exactly the same.'

Denying that he had received a 'chilly reception' from Congressmen and Senators during his Washington trip, Saran said all of them agreed that the nuclear deal was an important element of the emerging Indo-US relations. The American lawmakers said they were questions that needed to be answered.