Thiruvananthapuram | Former Kerala Chief Minister V S Achuthanandan, who was admitted to a private hospital after suffering a cardiac arrest, is responding to treatment, hospital sources said.

However, the veteran CPI(M) leader remains in critical condition and is being treated in the ICU, according to a health bulletin issued on Thursday.

The 101-year-old was admitted last week and is under the care of a team of specialists who are closely monitoring his vital parameters.

Achuthanandan, a towering figure in Kerala politics, has been battling age-related health issues in recent years and has largely withdrawn from public life.

He is the last surviving member of the group that founded the Communist Party of India (Marxist) in 1964 following the split in the undivided Communist Party.

A lifelong advocate of social justice and workers' rights, Achuthanandan served as Kerala's Chief Minister from 2006 to 2011.