IN THE fading evening light, the wide boulevards of Luanda are virtually silent but for a ragged army of filthy street children running barefoot down the central reservation of Avenida de Commandante Valodia.
As they skip nimbly through petroleum-slicked puddles, the flickering neon de Beers sign in the skyline above them momentarily illuminates the palm-lined malecón. They are heading home to the sewers.
Towering over them, in the pristine skyscrapers and apartment blocks of the Angolan capital, government ministers, US oil-men and Lebanese diamond brokers look down from the comfort of their air-conditioned offices and homes.
In Luanda, the government is known to the poor as "el donos" - "the owners" - an apt description for there are few places on earth where the void between the rich and the poor is so terribly apparent. Western aid workers call Luanda "the city of a thousand smells". Public buildings stink of stale urine, water supplies are fouled and the stench of rotting rubbish piled by the roads is pervasive.
Below the streets, too, in complex sewers laid by the Portuguese settlers a century ago, a Dickensian nightmare is being played out as street children and rats desperately compete for scraps of food.
By 9pm, the rambling downtown area of Zinga is in darkness, thanks to another powercut. In a sewer deep beneath the streets, Pazinho stares through candlelight with glazed eyes and slurred speech. In his hands is a cloth dipped in petrol, "ngue", he slurs. The concoction is foul, a mixture of raw sewage and petroleum. It’s used not only to give him a high, for the starving children it suppresses the appetite and dulls the pain and cold they experience in the sewers each night. "We’re lucky it’s so cheap," mumbles Pazinho.
Pazinho is ten and has lived and slept in this sewer beneath Luanda’s streets since 1999. He’s originally from Caxito, 40 miles away, but is unsure where his parents are. He is very small for his age and constantly looks up to the older boys for confidence.
"I want to leave this place," he says. "I lost my parents during the war, I don’t know where they are. I came here with my brother to hide from the army but I don’t know where he is now."
In times of war or peace, Luanda’s most distinguishing feature remains the Ilha, the sandy peninsula that acts as a breakwater between the south Atlantic and the Angolan capital.
At the height of the country’s devastating 15-year civil war, a favourite way for the army to clear the city of street children was to herd them in droves at night and take them in helicopters out to sea - before dropping them hundreds of feet into the ocean.
Today, the punishment for the street children rounded up by the police is less deadly but still draconian, with youngsters regularly imprisoned and "Sjamboked" - whipped on the soles of their feet and palms with police batons. The pain is unimaginable and unforgettable. The merest sight of police causes the children to flee to the sewers, wincing in pain at the very real memory of torture.
Yet for most of the children there are few options but to run this gauntlet of intimidation. Faced with starving to death in the countryside, rummaging through rubbish and eking a bare living in the towns and cities is the only way to survive.
For UNICEF, one of the few agencies to work with Luanda’s growing army of street children, their plight is one of the greatest tragedies of all in a city that simultaneously boasts more wealth and poverty than almost anywhere else in Africa; beyond the skyline, buried deep beneath the Atlantic, is a vast reservoir of oil.
According to James Elder, a field officer with UNICEF, the organisation provides two types of support to the children. He said: "UNICEF gives financial support and training to existing groups who focus on the most vulnerable of all street children, the very youngest boys and the girls. Likewise, as a way of breaking the cycle and offering street children an alternative future, we provide basic education and skills training to groups of street children.
"This is a big task for us. Millions flocked to Luanda during the war and many arrived with nothing. But we are committed to ensuring these children have a peace worth living."
These appalling scenes of lost youth can be found across Angola. In the provincial town of Lubango, 400 miles north of Luanda, I meet eight-year-old Antonio Saca, who has been on the streets since he was six. Barefoot, in ragged jeans and an oil-stained Mickey Mouse T-shirt, he leaves the pungent stench of malnutrition and sweat on my palm as he nervously shakes my hand.
I ask him if he wants to go to school. Through blackened teeth he smiles and nods vigorously. He tells me: "I lost my mum in the war. All I know is she died when I was a baby. My brother brought me to the town from the countryside but abandoned me. I want to go to school and learn to read, but I need to feed myself. I’ve been working the streets, washing cars and selling lighters since I was six."
As he speaks, I know that without consistent help and guidance, Antonio will never see the inside of a classroom. His future is on the streets, whether as a child prostitute or a modern-day slave condemned to blackening shoes. The "Candonga", the black market, is the only thing that keeps the nation’s street children alive - standing in the gutter they sell everything from rotting fruit to individual aspirins. The disturbing reality in this devastated country is the fact that almost one in three children will not live to the age of five.
• To support The Scotsman/UNICEF Angola Children’s Appeal, send donations to FREEPOST 1501, Glasgow G2 6ZZ, quoting reference 33642033