Singh and the Congress chief placed flower petals at the samadhi of Indira Gandhi as vocalists sang hymns during a remembrance ceremony at tightly guarded Shakti Sthal in New Delhi.
Union Home Minister Shivraj Patil, Jammu and Kashmir Chief Minister Ghulam Nabi Azad, Delhi Chief Minister Sheila Dikshit, Union Minister of State for Urban Development Ajay Maken, Delhi Governor B L Joshi, former Bihar Governor Buta Singh and All India Anti-Terrorist Front chief M S Bitta were among those present.
Indira Gandhi was assassinated on October 31 in 1984 by her Sikh bodyguards in retaliation for Operation Blue Star at the Golden Temple in June of 1984.
Scores of Congress activists shouted "long-live Indira" slogans as an audio recording of her speech was played on loudspeakers after hymn-singing.