Now, he said, India also has the computer simulation capability to predict the yields of nuclear weapons - fission, boosted fission and two-state thermonuclear - of designs related to the May 1998 tests.

He pointed out that even Iyengar had agreed with the yield of the tests.

Though Iyengar does not dispute yield of the thermonuclear test, the conclusions drawn by him on the efficiency were 'purely speculative in nature', according to Chidambaram.

'Our results were so accurate that we announced the yield on the same day of the explosion, which no other country has done as science has evolved in the past two decades,' he said.

Chidambaram wondered how, without the knowledge of the design, the nature of fission-fusion break-up and quantity of thermo-nuclear material, Iyengar could calculate the efficiency the fuel burnt as 10 percent.

'No one outside the design team had the data to calculate fission-fusion yield break-up or any other significant parameter related to fusion burn,' he said. The size of the crater depended on the depth of burial of the nuclear device and nature of the rock medium.

Chidambaram said that India was the only country which had given out so much information on the tests and no more data could be revealed due to proliferation-related sensitivities.