Singh had said that he did not quite appreciate Jaya Bachchan, who was brought into politics by him, for siding with SP chief Mulayam Singh and staying back in a party that "humiliated" him.
However, this year in February, Singh took to Twitter and said he regretted his 'overreaction against' Amitabh Bachchan and the Bachchan family.
"Today is my father's death anniversary and I got a message for the same from Amitabh Bachchan. At this stage of life when I am fighting a battle of life and death I regret my overreaction against Amit ji and family. God bless them all (sic)," Singh wrote on Twitter.
Earlier today, Singh wished everyone Eid Mubarak on Twitter. He also paid a tribute to freedom fighter Kokmanya Gangadhar Tilak on his death anniversary.
Meanwhile, Prime Ministr Narendra Modi expressed his condolences to the family of Amar Singh and tweeted, "Amar Singh Ji was an energetic public figure. In the last few decades, he witnessed some of the major political developments from close quarters. He was known for his friendships across many spheres of life. Saddened by his demise. Condolences to his friends & family. Om Shanti".
Defence Minister Rajnath Singh said the former Rajya Sabha MP had friends across the parties during his active years in politics.
Union Minister Nitin Gadkari wrote that he felt sad to hear the news of the demise of Amar Singh. "May his soul rest in peace".
Singh was first elected to the Rajya Sabha in 1966 from Uttar Pradesh. He was re-elected to the Rajya Sabha in June 2003, as well as, in 2016 from UP only. Over his decades-long political career, Singh was part of a number of parliamentary committees.
Singh was born on January 27, 1956, in Aligarh district of Uttar Pradesh. He was an alumnus of the St. Xavier's College and University College of Law, Kolkata.