Kolkata, Jan 6 - Veteran Communist Party of India-Marxist (CPI-M) leader Jyoti Basu's health deteriorated early Wednesday. The nonagenarian had trouble breathing, and the team of doctors treating him at a private hospital here since last week decided to put him on artificial ventilation.

"His condition is serious," the hospital's Medical Superintendent Debasish Sharma told IANS.

"Basu has been suffering from respiratory trouble and in the early hours of Wednesday, he started feeling unwell. The doctors immediately put him on ventilation," the former West Bengal chief minister's personal aide Joykrishna Ghosh told IANS.

Basu, 95, was hospitalised last week after a pneumonia attack and admitted to the Intensive Cardiac Care Unit of a private hospital in Salt Lake, the Kolkata suburb where he lives.

According to the medical bulletin issued Tuesday evening, Basu was on a liquid diet and his blood pressure was normal. The doctors had started physiotherapy.

Born in 1914 in Kolkata, Basu became chief minister in June 1977. He stepped down voluntarily on health grounds in November 2000.

One of the founding fathers of the CPI-M, Basu almost became India's prime minister in 1996, but the party vetoed the proposal. (IANS)