BBC correspondent Daniel Lak reports on a 'tough session in parliament'

Mr Vajpayee was speaking during India's first parliamentary debate since conducting a series of nuclear tests at Pokhran in the Rajasthan desert.

Atal Behari Vajpayee speaking in the Indian parliament

During the debate, the government came under fierce attack from opposition parties over the series of five tests conducted earlier this month.

A senior Congress MP said there was no evidence of declining national security at the time of the tests and the motive was to build domestic political support. A veteran communist leader said ministers were being too provocative in the wake of the tests, and risking a regional arms race.

The explosions prompted widespread international criticism and led to economic sanctions by a number of countries.

During the debate, Mr Vajpayee insisted that India was only interested in self-defence and was committed to international disarmament.

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He also said that India wanted talks on a nuclear weapons convention, along the lines of existing multilateral pacts to ban chemical and biological weapons.

No move yet from Pakistan

Meanwhile, the President of Pakistan, Rafiq Tarar, has said Islamabad has yet to make a decision on whether it will detonate a nuclear device in response to the Indian move.

He said that the country's Prime Minister, Nawaz Sharif, would announce his plans soon.

Pakistan has been coming under strong international pressure - particularly from the US - not to follow India's example and carry out nuclear tests.

Reports in the US this week said preparations were underway in a remote area of Pakistan for a test.

However, the US administration says it has been assured by Pakistan that it has not yet decided whether to go ahead.

"Pakistani officials have made clear publicly, as recently as today, and privately to us and others that they have not yet decided to carry out a test," State Department spokesman James Rubin said.