When Um Noor’s husband was blown to pieces by a car bomb last year, she drew comfort from the thought that she and her five children could at least depend on their close-knit community for support.

But Um Noor, a fragile figure barely 5ft tall, was a Sunni in the predominantly Shi’ite Baghdad district of Amil, and sectarian strife was taking the city by storm.

Soon her brother was murdered by a Shi’ite gang that spotted him in the street and chased him into a neighbour’s house where he was shot in cold blood.

Then the death squad burst into Um Noor’s own home and dragged away her eldest son and a nephew only six years old. They, too, were shot, just for being the sons of Sunnis.

Um Noor fled to a Sunni area where she believed she would find sanctuary, only to be warned that her remaining children were at risk from hitmen on her side of the sectarian divide. The reason: her husband had been Shi’ite. That made her children Shi’ites - potential targets for Sunni gunmen with a particular distaste for mixed marriages.

She now keeps the children locked in a borrowed house: two sons and two daughters aged 11 to 22 who hardly dare to feel the sun on their faces, let alone go to school or earn some much needed cash.

Um Noor has resolved to keep them there along with her late brother’s children - the eldest aged seven, the youngest a girl of six months - until order is restored in Baghdad. The way the US-Iraq security plan for the city is going, they could be in for a long and perilous wait.

Until March last year, Um Noor thought little of politics or such apparently trivial matters as which of her neighbours were Sunni or Shi’ite.

When she married Abdul Zahra, an electrician, more than 20 years ago, nobody cared that they were from different sects. They moved into an apartment he built on the roof of her parents’ home and had three sons and two daughters.

The fall of Saddam in 2003 barely touched their family, but the bombings and shootings that followed began taking a toll on the lives of those around them.

Two years ago the first reports of ethnic cleansing in Baghdad chilled the family’s hearts. Yet Um Noor, like many women in mixed marriages, felt safe. Surely, she reasoned, anyone could see that being married to a Shi’ite was proof that she was nonsectarian. She thought she was above the fray.

This sense of security was shattered by the bomb that exploded on a road as her 53-year-old husband happened to be passing on his way to a job.

Her grieving was compounded by fear, as fighting broke out last summer between the Shi’ite majority in Amil district and Sunni members of the Janabi tribe, to which she belonged. Hundreds were killed.

With nowhere else to go, Um Noor stayed put in the house where she had grown up. Her brother Raed al-Janabi, who delivered bread in the area, also remained with his family.

One August day she realised she had become an outcast among people she had known her whole life. “I awoke to find they had sprayed some writing on our gate,” she said last week. “As I couldn’t read, I asked my son to read it to me. It said, ‘Leave this house or else’.”

She was preparing dinner a week later when a neighbour’s children ran into the kitchen, shrieking: “Uncle Raed’s been killed.” They told her to follow them. “I felt the ground tilting under my feet,” she said. “I gathered my strength and ran after them.”

The children entered a house nearby. “The family were all standing there, their faces pale,” she said. “The women were crying and lamenting. I took a few steps into the corridor and saw him. He was lying on the ground, shot three times - once in the head and twice in the chest. After that I don’t remember anything.”

Later she heard that he had panicked when he realised he was being followed by men from the Mahdi Army of the radical Shi’ite cleric Moqtada al-Sadr, and had taken refuge in the first house he saw.

“They followed him in and killed him,” Um Noor said. “It was a good thing they didn’t kill everyone in the house for harbouring a Sunni.”

She knew she had to get her children and her brother’s family out of the district but there was a delay while she sold her television and refrigerator to raise the money for a removal van. It was only 24 hours, but it would cost two more lives.

As they waited for the van, Um Noor’s eldest son, Ali, 20, and her little nephew Ahmad went to say goodbye to friends. Suddenly there was a commotion outside. “Men stormed into our house. They were carrying weapons and their faces were covered,” she said. “They ran all over the house, shooting out the window panes and breaking all the kitchen things and everything they could find.”

One of the men was shouting in her face, “Where’s your bastard son?” referring to Ali. “And where’s that young snake [Ahmad]? You know the proverb - do not kill the snake and leave its young.”

Terrified for her own son’s safety, Um Noor could barely believe that the men could want her brother’s child as well. She cursed them, screaming for her family to be left alone.

By now Ali had heard about the intruders. As the man of the house since his father’s death, he regarded it as his responsibility to protect his mother. He ran in, with Ahmad in tow.

“As he barged in, they laughed,” his mother said, weeping. “They took the boys outside and pushed them both into the back seat of their pickup truck and drove off.”

Some of the masked men stood in the street, apparently hoping Um Noor’s seven-year-old nephew Abdullah would appear and ignoring her hysterical pleas for them to leave.

“I shouted and beat my breast and yanked my hair in the street but no one could do anything. A few minutes later we heard shots. I knew they [Ali and Ahmad] were dead,” she said.

“A pain came into my heart. I couldn’t cry. I couldn’t speak. I sat on the ground until my daughters dragged me inside. All I knew was that I had to save the others.”

The remaining intruders eventually drifted away. A few hours later the removal van arrived and the family loaded what they could and drove away, leaving the task of retrieving the boys’ bodies to their neighbours.

Um Noor and her heavily pregnant sister-in-law, both mourning the loss of a son, drove their remaining children - six of them in all - to Abu Ghraib, a Sunni town 20 miles west of Baghdad. Her sister lived there and she knew that many displaced families had been taken in and placed under the protection of local insurgents.

“We were given a very small house, for which we were grateful,” Um Noor said.

So shocked was she at first that she did not weep, talk or eat for three days. When her neighbours delivered the bodies of Ali and Ahmad, she would not allow anyone else to bathe her son for burial. She performed the ritual herself in silence, then led the family to Abu Ghraib’s cemetery.

Um Noor now lives in constant fear that her fellow Sunnis in Abu Ghraib will discover her secret. If anyone knew her children were Shi’ites, they would be cast out or killed, she says.

“I’ve told them not to go outside, to keep to themselves and mind their own business. They stay indoors and moan. They get edgy and frustrated.”

Just in case any Sunni gunmen come to investigate, she has buried the identity papers that carry their father’s Shi’ite name.

The family cannot obtain the monthly food ration they used to collect in Baghdad, but local help is channelled to them by the Committee for the Support of Victims, an aid group which claims that the war has left up to 3m women to cope without a man.

“All the young men of the area divide their income between their families and the families of the many widows,” Um Noor said. “They each give us what they can afford – 10,000, 15,000 or sometimes 20,000 dinars (£4 to £8). We’re also supported by the mosques, which provide us with food donated by the families from their rations. They’ve taken special trouble to provide milk for the baby girl.”

Unable to watch the children go hungry, Um Noor has arranged to clean the home of a woman she knows in Baghdad once a week, even though the journey is dangerous. It is this woman who put me in touch with her so that her story could be told to illustrate the suffering of ordinary families assailed by remorseless killing.

General David Petraeus, the American commander in Iraq, briefed politicians and military leaders in Washington last week that the number of sectarian killings had been significantly reduced since the US “troop surge” began in mid-February.

The figures are indeed lower than they were at their peak. But they are rising again and plenty of new widows were created last week: 11 bodies were discovered in Baghdad last Sunday, 19 on Monday, 15 on Tuesday, 18 on Wednesday and 26 on Thursday - a total of 89 in five days.

Um Noor, like many of the widows, struggles to make sense of what has befallen her family. “I feel we are living in punishment for some unknown sins,” she said. “God in his infinite wisdom would not inflict such pain on his creatures otherwise.”

While she derives pleasure from her children and from her surviving nephew and her nieces, she cannot come to terms with the deaths of her loved ones. “I lost my husband, then my brother, but when they killed my son it was as if my soul was torn from me.

“Although I’ve lost a lot, there is more to lose. The war isn’t over and God only knows what tomorrow will bring. I will do anything - anything at all - to keep my other children safe.”

Times Recommends

• Rio Tinto four held as China prepares case
• Diplomats must keep heads down and trousers up
• When in Rome should one make like Berlusconi?