Sehgal (97) breathed her last at a private hospital at Kanpur.
"Shrimati Lakshmi Sehgal passes away at 97 in Kanpur... fierce freedom fighter for Independence of India... What a lady! Prayers for her soul! She was with Subhash Chandra Bose and the INA... The Indian National Army to fight against British rule," the 69-year-old actor tweeted.
She was very active during the Independence movement and had commanded the 'Rani of Jhansi Regiment' of the INA formed by Bose. A doctor by profession, Sehgal was working as a medical practitioner and a social worker. She was awarded Padma Vibhushan in 1998.
"Captain Lakshmi Sahgal... Grandmother of Shaad Ali, who directed 'Bunty Aur Babli' and 'Jhoom Barabar Jhoom'... condolences and prayers Shaad!
"Just yesterday Shaad sent sms to me on her condition that despite cardiac attack, continued to conduct herself with a fighting spirit (sic)," Bachchan further posted on the micro-blogging site.