It was Loung Ung’s English teacher who suggested she write down her memories of life under the Khmer Rouge in Cambodia. She was 15 at the time and living in Essex Junction, a small town in Vermont, having escaped from Cambodia to the United States five years earlier via Vietnam and a Thai refugee camp.

The transition for a war-weary child of 10 had been traumatic. Vermont is a very Caucasian state. Loung spoke no English, and she was desperate to put the war years behind her, having lost both her parents and endured starvation, forced labour and “retraining” as a child soldier. She was living with her brother, Meng, also a refugee, and his family, and coped by trying to be as American as possible. “I tried to suppress the war, to push it away. I had my hair done like Farrah Fawcett and stuffed myself with American food. I tried to be someone else. I played soccer and hoped the ball would hit me so hard on the head that I would get amnesia.”

Her teachers at Albert D Lawton junior high had little inkling of what she was going through, although they helped her learn some English. She is still friendly with one of the teachers, Linda Costello, who gave her extra tuition using flashcards. “She made a game out of it, I wasn’t pressured to learn.”

But Loung wanted to learn. She needed to know what children in the playground were saying about her before she hit them. Her suppressed rage over her lost childhood was directed at the classmates who ignored her. “The other kids didn’t want to hang out with an oddity. In Cambodia, I was regarded as precocious, pretty and clever. In Vermont, I couldn’t be precocious because I couldn’t speak the language, I couldn’t argue to prove I was clever and I wasn’t pretty because I wasn’t blonde and blue-eyed.” Mostly, she was left alone.

When she moved to Essex Junction high, a rural school of around 1,200 students, it became increasingly difficult to deny her war experiences. As she went through puberty, she felt out of control. She didn’t understand what was happening to her body (in a recent Radio 4 interview, she talked of “watching my body disappear” during the hungry years in Cambodia) and of being haunted by nightmares. At 15, they were so bad she considered suicide. “I went through a severe depression,” she says, “as I could no longer suppress memories of the war. No one understood what I had been through and was going through at the time. I actually tried to kill myself by taking Tylenol (a non-prescription pain reliever in the US) but stopped because I did not want my family to suffer any more. My English teacher suggested I write down my story as a way to help me deal with it. So began my own form of therapy.”

Ellis Severance, still teaching at Essex Junction, is acknowledged warmly in First They Killed My Father, just published in the UK. “Every time I think to myself that I cannot write about this, I remember you,” Loung writes in her closing acknowledgements. Today she recalls him as a big, jovial man. “If you gave him a beard and red suit he would be Santa Claus. He was big in stature and big in heart. He used to stand on the tables and sing and dance to students when it was their birthday. His many students adored him.”

For Loung, he was pivotal as well as fun. For one assignment, she wrote about her family and about Cambodia. He marked it A-triple-plus and told her to keep writing, saying:“You have something to say. Content counts.” It was the first piece of work that hadn’t come back covered in red ink. She wrote for herself, however, not for him. “He let me have my space. If he had pressured me, I wouldn’t have done it,” she says. Six months later she had 200 handwritten pages, but it was to be another 13 years before they became a book.

First They Killed My Father is Loung Ung’s account of her childhood. It is told in the first person because “I wanted my readers to walk the journey in my shoes, to live my life and not understand the chaos around me, to not know if my war would end in three days or four years. Most importantly, I wanted to write a human story, a story no politicians, journalists or soldiers could tell. It was a story about my family and our struggle to live life with grace, dignity and beauty, even if only for a few hours in our four years of hell. I wanted to give beauty to my family’s life and struggles. I wanted the world to feel my love for them, to know of their love for me, their sacrifice.”

In April 1975, when the Khmer Rouge arrived in Phnom Penh, she was just five. The soldiers were welcomed by crowds sick of the civil war that had been fought against the American-backed Lon Nol government. It was a short-lived jubilation. Within days the Khmer Rouge set about evacuating the city. Everyone was forced to march into the countryside to start Pol Pot’s agrarian revolution. Loung, her parents and six brothers and sisters were among them. The happy little girl playing hopscotch on Phnom Penh’s streets was about to get a remorseless lesson in brutality, a lesson that filled her with an anger and hatred that years later found expression in her book.

As a middle-class family, the Ungs were an obvious target for the Khmer Rouge. From the moment they left Phnom Penh, secrecy about their true identity was of the essence. At a checkpoint on their march to a labour camp, Khmer Rouge guards asked for any former government members, ex-soldiers or politicians to step forward to help form the new government of the Angkar. Those who did were led away to be executed in Cambodia’s notorious killing fields. Wisely, Loung’s father, a former member of the Cambodian Royal Secret Service, chose to join the line of peasants.

But it was a deception that could not last. The book’s central moment occurs one evening in December 1976, when two men in black walk towards their family’s hut. They ask her father to help them shift an ox cart. He knows it is the end, although Loung does not.

“Pa puts his hand on my head and tousles my hair,” she writes. “Suddenly he surprises me and picks me up off the ground. His arms tight around me, Pa holds me and kisses my hair. It has been a long time since he has held me this way. My feet dangling in the air, I squeeze my eyes shut and wrap my arms around his neck, not wanting to let go.

”‘My beautiful girl,’ he says to me as his lips quiver into a small smile. ‘I have to go away with these two men for a while.’” She never saw him again.

After this, the family was split up. Loung’s older sister Keav had already died in a forced- labour camp. Her mother sent Loung, another sister and a brother in different directions, telling them they must not travel together, they must take new names and they must not communicate. “She pushed me out, swatted me on the bottom and said ‘Get out’,” Loung told Radio 4. “After my father died I was clinging to my mother, I was seven years old. I harboured anger and resentment at her for 15 years - I didn’t know the Khmer Rouge were targeting the families of men they had executed.”

Ignoring her mother’s orders, she and her sister Chou, then aged 10, stayed in their new work camp until Loung was selected to join a camp of child soldiers, where she was taught to hate and to kill. “They wanted me to hate my parents, but the one thing I was certain of in all the chaos was that my father loved me, and I was able to hate the Khmer Rouge instead.”

She survived starvation, witnessed appalling brutalities and, miraculously, was reunited with her brother Meng and other family members after the Vietnamese defeated the Khmer Rouge in January 1979. By then, her mother, her younger sister Geak and 20 other relatives had been murdered.

Cambodia’s civil wars may be over but the country is still littered with landmines that will take generations to clear. School exercise books issued by CMAC, a Cambodian organisation dedicated to mine-clearing and education about unexploded ordinance, still have graphic cartoons on their covers warning schoolchildren of the presence of mines.

Loung Ung is now a spokesperson for the Campaign for a Landmine-Free World, an organisation sponsored by the Vietnam Veterans of America Foundation in Washington, where she now lives. In her lectures and her work, Loung uses her memories of the war to illustrate her arguments. It was her boss, Bobby Muller, who convinced her to turn that high school bundle of notes into a book. “Professionally, I wanted to write to reach a broader audience, using the book as a vehicle for me to talk about landmines, child soldiers, the tribunal for the Khmer Rouge. Personally, I wrote the book for me,” she says. “Most people don’t understand that it’s never a choice to forget or remember. The war is always there, in me, outside of me, in my sister, in my country. I can learn to heal, but I can never escape it.

“Writing is healing. Being able to name your enemies with words takes away their power. I was not about to let the Khmer Rouge keep my voice. By writing, I took back my voice and power from them.

“By pushing my finger into their eyes and faces I am able to say, ‘No longer will you rule over me; no longer will fear rule over me.’ I also wanted my nieces and nephews all over the world to remember, to understand, never to forget. I wanted them and the world not to force the survivors to be the only bearers of witness to our brothers and sisters. In man’s inhumanity to man, we are all and should all be, bearers of witness for our brothers and sisters.” She is slightly bemused by the acclaim her book has received, although she is hard at work on a sequel that parallels her life in the US with that of her sister Chou, who stayed in Cambodia. Two other brothers besides Meng - Khouy and Kim - also survived the war.

Loung is delighted that First They Killed My Father, published in the US last year, is being used in schools and colleges. Not only is it telling people about Cambodia’s history, it is also making pupils aware, she hopes, “of who they might be sitting next to”, of the trauma that refugees and asylum-seekers have to overcome. “My classmates,” she says, “never knew my story - because they never asked.”

First They Killed My Father is published in the UK by Mainstream Press at pound;15.99

* TIMETABLE OF TERROR: THE KHMER ROUGE YEARS

1970 Anti-Vietnamese riots in Cambodia lead to General Lon Nol, backed by the United States, seizing control of the government. As the Vietnam War continues, US and South Vietnamese troops enter Cambodia to attack North Vietnamese (Communist) bases.

1970-75 The Khmer Rouge guerrilla movement, led by Pol Pot, grows and controls more than two-thirds of the country.

April 1975 Pol Pot seizes the capital, Phnom Penh, and overthrows Lon Nol’s regime.

1975-79 The “killing fields”: An estimated1.5 million Cambodians, mostly educated professionals - including Loung’s parents and 20 other relatives - are executed by the Khmer Rouge or die in labour camps.

1979 Vietnamese seize Phnom Penh; Khmer Rouge driven into the countryside; guerrilla fighting continues through the 1980s. Loung, Meng and his wife, Eang, join the tide of refugees heading for Thailand by boat.

1991 Peace treaty ends civil war but Khmer Rouge refuses to disarm.

1993 Cambodia’s first democratic elections.

1996 Khmer Rouge splits. One faction ousts and imprisons Pol Pot, who dies in 1998.