Seniormost Left Front leader in West Bengal and long-time state general secretary of the All India Forward Bloc Ashok Ghosh was put on ventilator support at a city hospital on Tuesday.
The 94-year-old Ghosh was admitted to the hospital on Tuesday following lower respiratory tract infection, the hospital said in a statement.
"At present, he is in the ICU, on ventilatory support," the hospital said.
He was being administered intravenous antibiotics, with oxygen support and nebulisation.
Chief Minister Mamata Banerjee and Left Front chairman Biman Bose were among those who visited the hospital and inquired about Ghosh's health.