NEW DELHI, Sept 26: Prime Minister Narendra Modi on Tuesday greeted his predecessor Manmohan Singh on the occasion of the Congress leader's birthday. Singh turned 91 on Tuesday. Born in 1932 in a region that is now part of Pakistan, Singh served as India's prime minister from 2004-14. In a post on X, Modi said, "Birthday wishes to former PM Dr. Manmohan Singh Ji. I pray for his long life and good health." Singh, who served as the finance minister in the then prime minister P V Narasimha Rao-led dispensation from 1991-1996, is credited as a key architect of the economic reforms effected by the government that broke the stranglehold of socialist-era policies. Currently a member of the Rajya Sabha, Singh has been ailing for some time.