The CPI-M described veteran leader Samar Mukherjee, who died Thursday at the age of 100, as "a most exceptional, outstanding and dedicated" Communist leader.
A statement from the Communist Party of India-Marxist said Mukherjee was also a "valiant freedom fighter" and an able parliamentarian.
He was the oldest living member of the CPI-M.
"He dedicated his entire life as a Communist to the cause of the working class and to the exploited people of India," it said.
Formerly in the central committee and politburo, he was a special invitee to the central committee at the time of his death.
"Mukherjee played an outstanding role as a leading Communist parliamentarian," the CPI-M said.
"He won the admiration of leaders cutting across party lines because of his unambiguous commitment to the cause of the exploited masses...
"Rarely have we seen such an individual who sacrificed all personal interests, living a spartan life in a party commune in the service of the party. He was affable, easily accessible and loved by the people."