New Delhi, Oct 4 : Shakti Sinha, a 1979 batch retired Indian Administrative Service (IAS) officer and Private Secretary to late former Prime Minister, Atal Bihari Vajpayee passed away on Monday. Born on May 11, 1957, Sinha died of a heart attack in the national Capital. Condoling the death of Shakti Sinha, Ram Madhav, the former BJP National General Secretary and senior RSS leader, tweeted, "Shocked to hear about Shakti Sinha's demise. He was a member of the Governing Board of India Foundation and was scheduled to address a conference at Leh this Monday afternoon." Describing Sinha as a humble person and an intellectual, Ram Madhav expressed his deep condolences on his death. The Ministry of Culture also condoled the death of Shakti Sinha, who was the Director of the Nehru Memorial Museum and Library. Sinha, a 1979 batch IAS officer, worked closely with former Prime Minister Atal Bihari Vajpayee for nearly three-and-a-half-years. Sinha, who met Vajpayee in the 80s, started working with him as Secretary to the Leader of the Opposition in 1996 and continued to work with Vajpayee as a Private Secretary even after he became the Prime Minister. He has also written the book 'Vajpayee: The Years That Changed India' on Vajpayee's tenure as PM. Sinha had served as the Director of Nehru Memorial Museum and Library, Chief Secretary of Andaman and Nicobar Islands, Chief Managing Director of Delhi Transco Limited, World Bank and United Nations mission to Afghanistan, and held many top and significant posts. He was also associated with Observer Research Foundation and the Atal Bihari Vajpayee Institute of Policy Research and International Studies at Vadodara, Gujarat. At present, he was serving with the India Foundation as a member of the Governing Body. /IANS