The 22-member board, which has five new members, will take up the job of formulating a well-defined nuclear doctrine, including the fundamental issue of a minimum nuclear deterrent, according to a highly-placed government source.

M K Narayanan, former director, Intelligence Bureau, Fazal Mohammed, an economist formerly with the Planning Commission, Brahma Chellaney and B George Verghese, both from the Delhi-based Centre for Policy Research, are among the NSCAB's new members. The name of the fifth member was not available.

Prime Minister Atal Behari Vajpayee has already sketched out some of the salient features of the possible nuclear doctrine, including India's commitment to a no-first use policy and minimum nuclear deterrence.

Vajpayee is expected to expand on the deterrence issue in his address to Parliamenttomorrow. These two features are likely to be fleshed out in the NSCAB's assignment, the source said.

The broad parameters of the proposed nuclear doctrine would be to ensure India's security in a world armed with nuclear weapons. The PM has already indicated that India is not in favour of an open-ended nuclear weapons programme.

The objectives would be ensure that India is neither subjected to nuclear blackmail, nor vulnerable to a nuclear threat, especially from its nuclear-armed neighbours. ``So long as nuclear weapons exist in the world, and the probability of its use is taken to be a positive, India should have the capability to deter any attack'', sources said.

At the same time, India is unlikely to imitate the American nuclear doctrine, which called for a massive nuclear arsenal running into tens of thousands of nuclear warheads.

Consequently, India is determined to integrate maximum restraints into the operational structure of its nuclear arsenal.

The Indian nuclear doctrine is more likelyto be like that of the Chinese, which has limited itself to barely 400 nuclear warheads until now. Some experts feel there could also be similarities with the French nuclear doctrine based on the principle of ``proportionate deterrence'', with a capability to inflict damage proportionate to the kind of stake the other side has.

With the Pokhran tests ending the long-standing ambivalence about India's nuclear status, the need to have a clear exposition of the country's nuclear policy has assumed greater urgency. There is a growing interest among the other nuclear weapon powers on what shape the Indian nuclear doctrine will take.

As almost the entire gamut of foreign policy and diplomatic issues are looped to the country's nuclear stance, the formulation of a comprehensive nuclear doctrine will be a priority for the NSCAB, the source said.

Under the three-tiered structure of the NSC, the NSCAB's blueprint would be placed before the Strategic Policy Group for its consideration and approval. The SPG, whichforms the vital link between the Advisory Board and the NSC, will then make their own recommendations based on the NSCAB's inputs to the apex body.