Hassan Mahmoud has the build of a bouncer. But as he sits on a couch and talks about Iraq’s secret religious prisons his broad frame shakes, he clutches himself and weeps.

“It hurts me when I remember what happened,” he says, recalling his brush with death inside a Shia prayer room where he witnessed the beheading of a fellow kidnap victim.

In the war for Baghdad, mosques serve as garrisons. Sunnis use religious sanctuaries as strongholds to fight for mixed neighbourhoods. Shia extremists convert their mosques and prayer rooms, called husseiniyas, into execution chambers.

As Iraq falls apart, people like Mahmoud are now terrified by Baghdad’s places of worship, which they regard as potential gulags and gallows in the Sunni-Shia war.

In a quiet voice he tells of an ordeal many have suffered but very few have survived. In late August he was waiting for a lift home after registering for a training course at a technical college in southeast Baghdad. His decision to take a minibus would prove disastrous. Before it had gone 50 metres two men and a woman pulled out rifles and ordered Mahmoud and three other male passengers to put their heads down.

Soon he had been whisked into Iraq’s fundamentalist netherworld. The next 24 hours in a Shia husseiniya brought him deep into the world of militiamen — where executions are carried out on a whim and ransom money is extorted from victims’ families.

He remembers how he and his companions were dumped from the minivan and dragged into separate corners of a brick room where three guards shouted at them to keep their heads down and took their phones and money. There they waited for the sayed — the Shia prayer leader.

The sayed wore a black turban and cloak — the mark of a descendant of the Prophet Muhammad — and had a pistol tucked by his side. He asked each man where he was from. The first answered Amariyah — a Sunni enclave that Shia extremists believe is a terrorist den. Mahmoud’s stomach sank.

Mahmoud realised that if they knew he was a Sunni he would die. “I’m from the Mussawis in al-Amal,” he lied, giving the name of a Shia tribe. The sayed warned him they would see if his story added up.

The final two captives were also questioned. Before leaving the sayed asked each one to identify his mobile and give the name of a relative to ring.

First they came back for the man from Amariyah. Then it was Mahmoud’s turn. They put a gun to his head as they pulled his body and dumped him in another room. He could hear the sayed’s voice above him.

The sayed demanded to know more about his family and where they lived. He mentioned an acquaintance from college who had joined the Mahdi Army and was killed recently. One of the sayed’s men whispered in his boss’s ear. “We have our own intelligence. I was there the day of his funeral, tell me about it,” the henchman said.

Mahmoud knew the right answer. He described how his old colleague’s funeral tent had been pitched alongside that of another Mahdi Army member. Mahmoud glanced up. The guards grabbed him and returned him to his corner. All the captives waited now for hours.

At 2am the guards handcuffed them with white plastic-cuffs and bound their legs. First they grabbed the man from Amariyah and took him to an adjoining room. Mahmoud watched from his corner.

“They wrapped him in a nylon sheet. They held him on his side. He was begging. One man sat on his legs, the other on his hips. A third guy, in black, remained standing and took the sheath off his knife and yanked the guy’s hair and recited ya Allah, ya Mohammed, ya Ali (the revered Shia figure) and then called out the names of the Imams (Ali’s descendants) and rested the blade on the Amariyah guy’s throat.

“The guy begged them and screamed for God to save him.But the man started to cut and shrieked ya Allah, ya Allah. Then there was a cracking sound like a sheep being slaughtered. The man pulled off the Amariyah guy’s head. His eyes were still open.

“He wiped his blade with a cloth. I waited four hours but it felt like 400 years. When they came for me, I collapsed. They pulled me from under my arms. The sayed was there. I begged him, for God’s sakes, my father is sick and old. He will die from shock.” The sayed smiled and told Mahmoud they were releasing him. He was thrown in the back of a car, blindfolded, and taken to the Karrada district of Baghdad . Only when he got home did he discover that his family had paid $10,000 — a huge sum in Iraq — to free him. Mahmoud still dreams of the man being murdered. He wakes up screaming: “Don’t slaughter him. Please don’t kill him.”

The Times is the only British newspaper to maintain a full-time Baghdad bureau

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