The ex-president was tested positive for COVID-19 before the surgery and was hospitalised after being unwell.
Former President Pranab Mukherjee on August 10 underwent a brain surgery at the Army's Research and Referral (R&R) hospital for removal of a clot, sources said.
The ex-president was tested positive for COVID-19 before the surgery and was hospitalised after being unwell.
News agency PTI quoting sources said the former president successfully underwent brain surgery for removal of a clot at the Army's R&R hospital.
"He is critical and is on ventilator support," the sources also said.
Mukherjee, 84, said in a tweet in the morning, "On a visit to the hospital for a separate procedure, I have tested positive for COVID19 today."
"I request the people who came in contact with me in the last week, to please self isolate and get tested for COVID-19," Mukherjee, who was the president from 2012 to 2017, said.
Defence Minister Rajnath Singh visited the R&R Hospital and enquired about the former president's health. Singh was at the hospital for around 20 minutes.
(With inputs from PTI)