Former West Bengal chief minister Siddhartha Shankar Ray on Saturday night died at his south Kolkata residence after a protracted illness.
He was 90 and survived by his wife Maya Ray.
"Ray was ill for quite a long time and had been on dialysis since March. The end came at about 6:50 pm," his assistant M Kaviraj told PTI.
Ray, a close friend of former chief minister late Jyoti Basu, was elected as the chief minister in 1972. The Congress veteran, a former Punjab governor, had also served as the Indian ambassador to the United States.
A confidant of late prime minister Indira Gandhi in the 1970s, he was appointed union minister (in-charge of West Bengal affairs) by her in 1971. Ray was the grandson of revolutionary freedom fighter Deshbandhu Chittaranjan Das.
President Pratibha Patil and politicians, cutting across party lines, condoled the death of Ray.
"The nation has lost an eminent public figure," the President was quoted as saying by a Rashtrapati Bhavan spokesperson.
Railway Minister and Trinamool Congress chief Mamata Banerjee, who was the first to rush to Ray's Bhavanipur residence in South Kolkata, said Ray had championed the cause of the minorities.
Finance Minister Pranab Mukherjee said Ray occupied an important place in the politics of Bengal and was an able and experienced administrator.
"He took over the reins of a Congress government in West Bengal during a critical phase. But he tackled the situation as a capable administrator. Though we had differences in opinion, his political wisdom, administrative capability and honesty was beyond doubt," he said.
Veteran Left Front leader and State Secretary of Forward Bloc Ashok Ghosh said, "Ray was an honest and courageous leader. Though there were differences on ideology, we used to hold discussions on administrative affairs."
West Bengal Pradesh Congress president Manas Bhunia said the death of Ray, a former WBPCC chief, had created a void in politics.