The Indian Government has set up a formal command structure to manage its nuclear weapons.

An official statement said a nuclear command authority had been created comprising a political and executive council.

"The political council is chaired by the prime minister," the statement said, adding that it was the only body authorised to use nuclear weapons.

Both India and Pakistan carried out nuclear tests in 1998 - to widespread international condemnation.

No first use

The executive council, chaired by India's National Security Adviser, exists to carry out the orders of the political council, according to the government.

President Musharraf: Denied he was talking about nuclear arms

The statement also reiterated India's commitment not to use nuclear arms first in any conflict - but only in retaliation for a nuclear attack against it or its forces.

But it also said that in the event of a major attack involving chemical or biological weapons, India reserved the right to use nuclear weapons.

Defence analysts say the statement fleshes out India's original nuclear doctrine, announced in 1999 at the time of the Kargil conflict with Pakistan-backed forces in Kashmir.

They point out that the latest statement comes shortly after recent comments by Pakistani President Pervez Musharraf, which appeared to suggest that he would have used nuclear weapons if India had attacked last year.

The Pakistani leader subsequently denied he was referring to nuclear arms when talking about a possible war with India.

The two countries came close to war after an attack on the Indian parliament, sparking international fears of a major conflagration in the region.