The condition of former President Pranab Mukherjee declined on Monday morning and he has suffered a septic shock due to his lung infection, the Army's Research and Referral Hospital said.
Doctors attending on the 84-year-old Mukherjee said he continues to be in a deep coma and is on ventilator support.
Mukherjee is being managed by a team of specialists, they added.
The former president was admitted to the hospital in Delhi Cantonment on August 10 and was operated the same day for removal of a clot in his brain.
He later developed a lung infection.
"There has been a decline in the medical condition of Shri Pranab Mukherjee since yesterday. He is in septic shock due to his lung infection and is being managed by a team of specialists. He continues to be in a deep coma and on ventilator support," the hospital said in a statement.
Mukherjee was the 13th President of India from 2012 to 2017.
