The briefing followed Prime Minister Manmohan Singh's [Images] assurance to his predecessor Atal Bihari Vajpayee last week that India's strategic programme would not be impacted by the nuclear deal with the US.

Advani was in Singapore when Singh briefed Vajpayee and his party colleagues Jaswant Singh, Yashwant Sinha, Rajnath Singh and Arun Shourie about the salient features of the 123 Agreement.

The BJP has maintained that it will come out with its detailed comments on the nuclear pact after studying its text.

Party sources said that the NSA briefed Advani about the basic features of the nuclear deal, over which the BJP has its apprehensions.

The BJP, which voiced its concerns during the meeting with the prime minister, says its apprehension have not yet been dispelled completely.

Yashwant Sinha last week told reporters, after the meeting with the prime minister, that the text of the agreement was clearly frozen and neither India nor the US could now make any changes in it. He had said the government had not shared the text with the party leaders but shared only the main elements of the agreement.