Mohun Bagan president and retired justice Gitanath Ganguly died on Tuesday afternoon following a cardiac arrest, club sources said.
An eminent lawyer, Ganguly, 83, suffered a leg injury when his car was rammed from behind by another vehicle in an accident earlier this month.
Ganguly had to be operated upon but he could not recover fully.
"In the morning, he developed chest pain and breathed his last while being rushed to the hospital," a club official said.
Ganguly took over as the club president after the Swapan Sadhan Bose-led panel swept the elections in November last year.
A close aide of Bose, Ganguly was associated with the Mariners for a long time and was the club's legal consultant when Anjan Mitra was the general secretary.
Meanwhile Pannalal Chatterjee, who has attended 10 World Cups with his wife, died on Tuesday morning aged 86.
A retired Kolkata Port Trust clerk, Pannalal and his wife Chaitali began their love affair of visiting the World Cup since Spain 1982.
"Indian Football will miss Pannalal Chatterjee, one of the most ardent football fans across India. Rest in peace," tweeted I-League.
Delhi Football president Shaji Prabhakaran wrote, "My sincere condolences to family and friends of Mr. Pannalal Chatterjee. His passion and love for the beautiful game is inspiring and touching. He will always stay in my memory."
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