“Saddened at the passing away of Somnath-Da. My condolences to his family and admirers. This is a great loss for us,” the Trinamool Congress supremo tweeted.
Chatterjee, 89, breathed his last at a private clinic here following a cardiac arrest and prolonged illness.
The former Communist Party of India-Marxist (CPI-M) leader, who was expelled from the party in 2008, after representing it since 1968, was critical following the heart attack he suffered on Sunday.
The 10-time MP was also suffering from a kidney-related ailment and was admitted to the Bellevue Clinic in a critical condition on August 7.