Before the prayer meet, the family of the former PM would also hold a 'bhog' of the 'Akhand Path' kept in the memory of Singh at their 3, Motilal Nehru Marg residence.
Singh, who steered the country as prime minister from 2004 to 2014, was considered the architect of India's economic reforms in the 1990s.
He died at AIIMS Delhi December 26. He was 92.