Sanyal, 57, had joined the Aam Aadmi Party after quitting her job as the country chief executive of Royal Bank of Scotland, and contested the Lok Sabha election in 2014.
AAP leader and Delhi's Deputy Chief Minister Manish Sisodia confirmed her death in a tweet, saying the country has lost a 'sharp economic brain and a gentle soul'.
'You will forever remain in our hearts,' Sisodia said in the tweet.
'Extremely sad to hear this. No words to express...,' AAP chief and Delhi Chief Minister Arvind Kejriwal tweeted.
In her 30-year-old banking career before surprising all by plunging into politics, the Kochi-born Sanyal had also served as the head of corporate finance and chief operating officer for ABN Amro for Asia.
She unsuccessfully contested the 2014 Lok Sabha election from Mumbai south constituency.
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