Jawad, a busy surgeon and a Sunni, thought he was going to be urged to smuggle drugs out of the building so that they could be sold on the street. But the brutal proposition from the porter Ali, a Shi’ite from the Sadr City suburb of the capital, was far more shocking.

For every patient the doctor identified from the predominantly Sunni provinces of Diyala and Anbar and from the Adhamiyah district of Baghdad, he was told, he would be paid $300 (£151).

Jawad realised that he was being invited to pass death sentences on patients at the Medical City hospital in return for swift and surreptitious payments.

“You can make a fortune,” Ali told him calmly. “Doctor, if you have those patients in the future just tell me and I will give you $300 just for that information . . . and do not tell anyone about this little talk.”

In an e-mail sent to The Sunday Times through intermediaries last week, at considerable risk to those involved, and in telephone interviews, Jawad — whose name has been changed for his protection — said the approach seemed to confirm his suspicions that some Sunni patients were being kidnapped by Shi’ite militias.

He believed that others were being murdered in their beds with drugs, such as an anaesthetic capable of causing a heart attack, he said.

Jawad’s concerns are shared by a growing number of doctors, patients and government officials, who are suggesting that Baghdad’s hospitals — supposed havens from the fighting — are being drawn towards the frontline in the spreading sectarian conflict.

There is said to be mounting evidence that Shi’ite death squads are being encouraged to roam hospitals in search of fresh Sunni victims, allegedly at the behest of officials in the Shi’ite-dominated health ministry.

During the summer Jawad first became worried by the mysterious deaths of several patients who had been transferred from American field hospitals.

As others went missing, often in strange circumstances, he learnt that the Mahdi Army of the radical Shi’ite cleric Moqtada al-Sadr had infiltrated the Medical City’s porters and cleaners.

“I’m an Iraqi doctor, working in one of the biggest hospitals in Iraq and I want you to read this carefully because the suffering and the lives of many poor people have become the cheapest things that you can buy in my country,” Jawad’s e-mail began.

The patients who were disappearing and dying were often civilians injured by crossfire in shoot-outs, he noted.

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