Amar Singh is currently undergoing treatment at AIIMS after he showed signs of "fluctuating" health".
Singh was admitted to AIIMS following complications related to post-renal transplant, diarrhea, urinary tract infection, diabetes, dehydration and hypothyroid hypertension, Sanjay Gupta, additional professor of the department of nephrology at AIIMS, said in his report.
Amitabh's visit comes as a surprise after there was a fallout between Singh and the Bachchans. [Read more: Friends turn foes: Amar Singh exposes Bachchans?]
The Bachchans were also cricticised by Jaya Prada, a close aide of Amar Singh after she ostensibly referred to Amitabh Bachchan and his family in her statement. [Read more: Jaya Prada comes in rescue of Amar; guns for Bachchans].
"The big celebrities whom he helped, he fought to get them land...the famous people, where are they?" Jaya Prada had said after celebrities and politicians failed to sympathise with Amar.
Amar Singh was arrested on Sept 5 for his involvement in the cash-for-votes-scam. He was given interim bail till Sept 19 on health grounds.