Renowned Carnatic singer M S Subbulakshmi, who is undergoing treatment in a private hospital in Chennai, is 'very critically ill', hospital sources said on Saturday.

• M S Subbulakshmi hospitalised

The octogenarian artiste, popularly known as 'MS', was admitted to the hospital on December 2 after a bout of viral infection, which was diagnosed as 'broncho pneumonia'.

Initially, she responded to treatment. But on December 9, she developed 'irregularities' in heartbeat, the sources told PTI. Since Friday night, her condition has got worse, they added.