New Delhi, Aug 6: R.K. Dhawan, once the powerful aide and confidant of late Prime Minister Indira Gandhi, died here on Monday in a hospital after a brief illness.The 81-year-old Dhawan, who married only six years ago, had been unwell in the last five-six months and had been in and out of hospital, sources in his household said. As Personal Secretary to Gandhi, Rajinder Kumar Dhawan wielded enormous clout with his presence in the PMO and the household, especially during Emergency, by keeping a hold on who got access to the Prime Minister. He was a witness to India Gandhi's assassination in October 1984 and had appeared as witness before the Thakkar Commission of inquiry which pointed the needle of suspicion on him. Rajiv Gandhi, who succeeded his mother Indira Gandhi, was not very enthusiastic about retaining Dhawan in his office. However, Dhawan made a comeback, rising to become a Member of Parliament and was inducted into the Congress Working Committee. The Congress on Monday expressed sadness over the passing away of Dhawan whom it described as a valued member of the party. Former President Pranab Mukherjee, a veteran Congressman himself, said he was deeply shocked by the death of Dhawan who he said was a close associate and colleague in the party and the government. "Though he was ailing, I had never expected that the end will come so soon," he tweeted, adding he would forever be fondly remembered. Senior Congress leader and party General Secretary Ashok Gehlot said he was saddened by Dhawan's death. His contribution to the Congress would always be remembered, he said. Congress spokesperson Randeep Singh Surjewala said Dhawan's tireless spirit, immeasurable commitment and untiring dedication to the Congress ideals would always be remembered.