CPM sources said the 96-year-old leader was advised hospitalisation by doctors for tests after he complained of breathing trouble due to severe cold. Doctors said his condition was not critical.

Basu stays alone at Indira Bhawan in Salt Lake and is looked after by Joykrishna Ghosh, his personal assistant.

Basu’s son Chandan, CPM state secretary Biman Bose, state Finance Minister Asim Dasgupta and Lok Sabha Speaker Somnath Chatterjee were among those who came to the hospital.

In July 2009, Basu was admitted to the same AMRI hospital near his residence after he fell in his bedroom. Since then, an attendant has been appointed to stay at his residence.

CPM sources said Basu has no regular health problems, excepting irritable bowels syndrome. He has been avoiding regular visitors for the past few months.