Former Union Minister Jaswant Singh is in a critical condition after being operated upon for a head injury at the Army Research and Referral Hospital in New Delhi following a fall at his residence. br br The 76-year-old former Defence Minister was admitted to the hospital at around 11 p.m. on Thursday after he fell down, sources said. br br A senior doctor at the hospital on Friday said that Mr. Singh has been operated upon for head injury and he is in a critical condition in the ICU.