PESHAWAR: The boy was two when his mother dumped him on the streets, four when he spent his first night in a tiny prison cell, being sexually assaulted by an older inmate. Prostitution for money and shelter followed then hashish, and glue-sniffing.

Now 10 and gangly, he fidgets and stares at the ground, speaking in a near-whisper. "I'm ashamed," he says.

Yet in this rugged frontier city in northwest Pakistan, where people carry guns as casually as they would a daily newspaper, this boy has hope. He has found refuge in what for Pakistan is relatively rare: a charity-run boarding school for homeless, drug-addicted children.

Around Peshawar, heroin sells for less than $0.20 a high. "It's the cheapest place in the world to get heroin," says Mazahar Ali, the school's manager. He gestures beyond the school's high walls. Heroin and just about every other vice are just a short walk away, he says.

The drugs all come from nearby Afghanistan which, according to a 2011 UN report, provides 90 per cent of the world's opium, from which heroin is made.

For Pakistan, the result is more than four million addicts. Some of the youngest end up in mud-walled rooms being drilled in extreme Muslim doctrine by the Taliban who roam relatively freely in Peshawar.

"Sometimes the militants take these children to North Waziristan and teach them to be suicide bombers and sometimes they give the children drugs and the child might not even know that he is going to be blown up," says Ali.

At the school, a boy named Osama told of memorizing the Quran while the Taliban hovered over him. He said he was tortured. He escaped, and a month ago was found sleeping on the floor of a ramshackle hotel, said Umaima Zia, the school psychologist.

On the lawn in front of the four-story school, Osama sat cross-legged on a chair in the afternoon sun, his small body swaying as he recited Quranic verses to his fellow students in a lilting voice.

A single working woman aged 25, Zia is unusual in this conservative region where girls are often married off soon after puberty.

Quick to smile, she gently draws out the kids' accounts of what they have endured. She brings stuffed animals to the school, and even the older boys cling to them. She gave the sexually assaulted boy a furry lion-shaped hat which he rarely takes off except for prayers.

A while ago that child's mother was found, but she would not take him back. "She didn't want me," he muttered, almost inaudibly "She said I was garbage."

The Associated Press does not identify, in text or through images, persons who say they have been sexually assaulted.

Children generally stay three months at the boarding school, long enough to detox. Run by the Dost Foundation, a family-owned charity, it has 32 boarders, all boys. A separate facility for girls is planned, because mixing of the sexes in Pakistan is shunned. Zia told of finding one little girl knocking on car windows asking 50 rupees to bare her chest to the occupants. She was six.

"It's sad, so sad that there is nothing for girls here," she said. "Most of the girls are homeless. Not so many are drug users. Many are scavengers but they are very vulnerable to abuse."

Eleven of the boys in the school are intravenous drug users and two have Aids.

Dr Sikander Khan, whose family started the charity 20 years ago, says the Aids problem is getting worse. Pakistan is a poor country, and 70 per cent of its 180 million people are under 30 years old, with more children using drugs intravenously and Aids rates rising, Khan said.

Khan, a physician who interned in New York, estimated roughly 7,000 children were living homeless on the streets of Peshawar.

He said roughly half of Pakistan's heroin addicts are believed to be intravenous users, a dramatic change. Discussion of sex is taboo, and although the UN estimates there are 97,400 HIV patients, only 4,112 are registered.

Khan's charity also supports community-based schools and provides rehabilitation facilities for adult addicts as well as vocational training for young boys and girls. It gets money from the European Union, US and UN, but Khan says it is short of funds and has had to close some of the schools.

"There is a lot of (international) funding for infrastructure like roads, but when it comes to drugs, when it comes to street children and shelter homes, the funding is not there or it is very small," said Khan.

But he said the trend might be changing, if only because of the fear that the neglected children will become Taliban fodder.

He said there is evidence this recruiting is happening. There's no certainty the children are being turned into terrorists, but he sees a growing recognition that they are exploitable and need help.

Inam, 15, has been through detox at the boarding school several times. Short and squat, he is notorious as Peshawar's most accomplished pickpocket — so notorious that he was the subject of a documentary. He has his own gang, has been in prison on attempted-murder charges, keeps police officers on his payroll and has scars on his leg from acid thrown by rivals who tried to steal his gun.

A month ago he discovered he has HIV, and his tough-guy image crumbled. He believes he got the virus from sharing needles with other drug users. As he spoke his eyes grew wet, but he quickly wiped them with his sleeve and composed himself.

On the wall of the children's dormitory, a poster tries to offer hope with words in English written against a backdrop of hellish red flames: "I am in hell but that doesn't mean I will stay forever."