Former Indian President Pranab Mukherjee, who had tested positive for COVID-19, died of multiple organ failure at the age of 84 on Monday after weeks in hospital, his son and the current president's office said. 

A veteran politician who served as foreign and finance minister in previous administrations, Mukherjee was in a deep coma and on ventilator support after coming down with a lung infection. 

"His demise is passing of an era," the office of President Ram Nath Kovind said in a tweet. 

Mukherjee, India's 13th president from 2012-2017, tested positive for COVID-19 on August 10 and had been hospitalized since. He underwent brain surgery at a military hospital in New Delhi.

Indian Prime Minister Narendra Modi offered the nation's condolences on the death of Mukherjee, saying the former president "has left an indelible mark on the development trajectory of our nation." 

Mukherjee was a protege of late Preme Minister Indira Gandhi and was a member of her cabinet when she suspended democratic rights in the infamous "emergency" of 1975-77.  

His star waned after Gandhi's assassination in 1984 when he was a rival to her son and heir Rajiv Gandhi for leadership of the Congress party.  

Mukherjee briefly broke away from Congress, but after Rajiv Gandhi was killed in 1991 his political fortunes were revived. He became Prime Minister Manmohan Singh's right-hand-man during his decade in power from 2004-14, serving as defense, foreign and finance minister and winning a cross-party reputation as a skilled negotiator.  

However, Mukherjee's performance as finance minister was criticized for his failure to push through economic liberalization measures.  

In 2012 he moved away from active politics and assumed the largely ceremonial role of president. 

(With input from AFP, Reuters)