The condition of CPM patriarch Jyoti Basu remained 'very very critical' on Saturday following multi-organ failure and doctors said he is entirely on life support system.

"He is entirely on life support system ... He is on full ventilation," Debashsis Sharma, Superintendent of the AMRI Hospital in Salt Lake, where the 95-year-old former West Bengal chief minister is admitted, said.

Basu's lung, kidney and haemo-dynamic system had failed on Friday and heart and liver functions had been affected.

He will now be put on slow, low efficiency daily dialysis.

Basu's family members were called by the hospital late on Friday night as his blood pressure sank suddenly. The blood pressure was stabilised to an extent after administering a new medicine.