A senior doctor in prestigious Indraprastha Apollo hospital in New Delhi on Tuesday allegedly committed suicide by swallowing poisonous substances in his office, police said.

Forty-years-old Umesh Chandra Sharma was the head of the emergency medicine department of the premier hospital in South Delhi.

Initial investigation revealed that he was depressed due to family problems.

"We are speaking to his family members and friends to know why he took the extreme step. It seems he was disturbed because of some family problems," a senior police official said.

A distinguished clinician and alumni of Armed Forces Medical College, Sharma was found unconscious in his office on Tuesday morning by his colleagues.

According to his friends, he had complained of stomach pain on Monday after which he was admitted to the hospital.

Sharma was discharged early on Tuesday morning.

He, however, turned up for duty at around 6 am. Later, he was found unconscious in his office, police said.

A one-line suicide note found from his possession said nobody was responsible for his death.

Sharma had re-joined the hospital as Head of Department, Emergency Medicine, in May 2006 after he had left it for pursuing higher studies.

He had worked in the hospital for close to eight years and was the quality manager assigned to liaison with police when late BJP leader Pramod Mahajan's son Rahul was admitted there due to drug abuse.

Sharma obtained a degree in emergency medicine from the UK and a diploma in cardiology from Georgia.