Kolkata: A man in a white coat allegedly hired on a "doctor's fee" of Rs 8,000 to accompany an ailing Madhyamik examinee in an ambulance turned out to be an air-conditioner mechanic after the meritorious boy was declared dead on arrival at a city hospital.

Police said the man had placed an oxygen mask on 16-year-old Arijit Das and said he thought that was enough to sustain him over the 100km journey from Burdwan to Kolkata.

A nursing home near Burdwan town, which accepts referring the patient to Kolkata but denies the family's allegation of arranging for the ambulance and charging fees for the "accompanying doctor", said the boy had "respiratory problems" but did not offer a diagnosis. The preliminary post-mortem report is pending, the police said.

"He (the man in the ambulance) said he had worked with doctors and could carry out instructions to operate oxygen cylinders on patients," a police officer said in Kolkata. "He claimed he had worked as an AC mechanic and had thus learnt to handle gas cylinders. We are verifying all the claims."

Son of a homoeopath and an anganwadi worker, Arijit had topped his December school exams with 96.25 per cent marks. An uncle said Arijit wanted to be a doctor and treat poor villagers.

Arijit, a resident of Nalhati in Birbhum, had complained of back pain and fever after writing his geography paper on Wednesday. Still in his school uniform, he was taken to Rampurhat Sadar Hospital.

On Thursday, he was referred to a government hospital in Burdwan. But, according to his family, the driver of the vehicle driving them from Rampurhat to Burdwan persuaded them to take the boy to Annapurna Nursing Home at Phagupur on NH2.

At night, the nursing home said the boy needed to be treated in Kolkata. The family say they paid a purported representative of the nursing home Rs 8,000 for the ambulance and another Rs 8,000 as fee for the "doctor" who would accompany the patient.

None of the relatives was allowed to be by the patient's side in the ambulance. "The family was told that a doctor of this stature does not allow relatives to travel in the same ambulance," an officer said.

The vehicle reached the Rabindranath Tagore International Institute of Cardiac Sciences in Kolkata around 11.30pm on Thursday. Arijit was declared dead at the hospital.

It was after reaching the hospital that the family grew suspicious. "I asked the 'doctor' in the ambulance his name and registration number so I could check his details on the Net. He fumbled and said, 'Sanjay Biswas'. But when I grilled him about Arijit's medical condition, he said he was a 'technical person'. After five minutes, he said he was an AC mechanic," said Arijit's uncle Subhendu Mandal.

Officers identified the man as Sheikh Sarfarazuddin. The 25-year-old and the ambulance driver, Tara Babu Sha, 26, have been arrested and charged with causing death due to negligence, cheating, threatening to cause death or grievous hurt, and common intention.

The Burdwan nursing home's manager, Sheikh Rabiul Islam, said: "We had no role in arranging the ambulance; the patient party arranged for it themselves."

The ambulance, which has "Burdwan Physical Cultural Centre" painted on it, appeared to be owned by a local club, like many ambulances in the state are. Multiple calls by this newspaper to a phone number printed on the ambulance went unanswered.