The veteran Left leader has been put on ventilator support at the city nursing home since last Tuesday following a kidney-related ailment.
The 89-year-old was earlier admitted to the nursing home on June 25 after suffering a haemorrhagic stroke.
He underwent treatment for 40 days and was discharged just for three days after his health showed signs of improvement. However, he was re-admitted after his condition deteriorated last Tuesday, the officer said.
The 10-time Lok Sabha member was expelled from the Communist Party of India-Marxist on July 23, 2008, "for seriously compromising the position of the party" as he refused to resign as the Speaker after the CPI-M withdrew support to the first United Progressive Alliance government over the India-US civil nuclear deal.
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