On Board Air India One, Sep 23 - The government has rubbished the claim by a retired senior scientist that the nuclear tests India conducted 11 years ago were a failure and questioned the timing of his statement.

'He is a perennial doubter. Why has he waited for five years of the UPA (United Progressive Alliance) government to make the claim?' a top government official said referring to the claim by the former scientist with a state-run agency.

'Out of eight different tests, one may not have yielded the same set of results that we may have talked about. But the rest of the seven have been a success,' the official said on condition of anonymity, during an informal interaction with journalists accompanying Prime Minister Manmohan Singh on way to Pittsburgh, US, for the G20 Summit.

The comments by the official were in response to the claim by K. Santhanam, a retired scientist of the Defence Research and Development Organisation (DRDO), that the nuclear tests conducted by India in 1998 were not a success.

The tests were conducted May 11, 2008 at Pokhran in Rajasthan during the National Democratic Alliance (NDA) government under prime minister Atal Bihari Vajpayee, following which India had to face economic sanctions.