We should conduct more nuclear tests which are necessary from the point of view of security'. Santhanam made these remarks to IANS Thursday.

This runs contrary to assertions by other scientists and top officials involved with India's nuclear programme.

R. Chidambaram, who was in 1998 chief of the Department of Atomic Energy (DAE), is on record as saying that the bomb's yield was 45 kilotonnes (45,000 tonnes of conventional explosive).

Santhanam's remarks have not gone down well with the government.

'I have seen the report. I am puzzled. The government will find out, somebody will brief you,' Home Minister P. Chidambaram said after a meeting of the cabinet committee on economic affairs.

Official sources dismissed Santhanam's remarks and underlined that India's opposition to CTBT remains unchanged.

'We will not be signatory to any agreement which is discriminatory in nature,' a source said.

Santhanam's remarks are bound to create a flutter in the non-proliferation establishment in the US and may raise fresh doubts about the future of the India-US nuclear deal which will unravel if New Delhi were to test again.

Santhanam's assessment is set to bolster India's opposition to signing the CTBT - an issue that may figure in the discussions when Prime Minister Manmohan Singh goes to the US in November.

India has opposed the CTBT on grounds that it is discriminatory and tends to divide the world into nuclear haves and have-nots.