The Mbare Flats in the slums of southern Harare are a complex of bleak, two-storey concrete blocks that make the unprepared visitor recoil in horror.

They are packed with the destitute and violent, rural labourers who have come to the capital in search of work, and those exploiting them — and with government informers.

The windows are smashed. The place stinks. It has open sewers and communal lavatories. Men hawk home-made alcohol.

We hurried across a courtyard, up a staircase and along a corridor, and there we found them — five children huddled in one small, dark room and left to fend for themselves in the most brutal surroundings.

There were three brothers and two sisters, aged 3 to 16, named Wish, Sythia, Dephine, Anesu and Given Nechavava. They looked frightened and bewildered.

The room was lit by a single naked lightbulb and divided by a ragged curtain. At the far end, next to the broken window, was a double bed covered in a filthy blanket on which all five slept.

At the near end were some old, sagging chairs, a primitive stove and a few cooking pots. The floor was bare. Dark green paint peeled off the walls.

The children’s father died of Aids in 2001. Two months ago their mother abandoned them. She simply walked out one night, saying that she was going to Mozambique, and never returned. A church worker found the siblings a fortnight later.

“It was terrible,” he said. They had no food, were very hungry and were begging. They still possess a small framed photograph of their parents, taken in happier times.

The Church is now giving them enough food to survive, employing two as cleaners and sending the other three to school. But these are stop-gap measures. “They have no future,” the local activist who took us into the flats said. “They’ll end up as street kids — the girls as prostitutes, the boys as thieves.” They were already easy prey for sexual predators, she added.

Of all the victims of Robert Mugabe’s regime, the children of Zimbabwe are the most vulnerable and heartrending. Their families have been destroyed by Aids, poverty and emigration. The social welfare systems that might have helped them have collapsed in the country’s economic meltdown. Millions go hungry. Many are severely malnourished.

Unicef estimates that 1.6 million Zimbabwean children, a quarter of the total, are orphans — the highest percentage in the world. The headmaster of a secondary school outside Bulawayo told The Times that a third of his 600 14 to 16-year-old students were parentless, and expected that number to rise by another 100 within a year.

In a rural primary school 30 miles (50km) from Bulawayo we found 16 orphans in a class of 32 six-year-olds. By some estimates as many as a third of Zimbabwe’s children no longer go to school.

Unicef believes that 90 per cent of those without parents are taken in by grandparents and other members of their extended families. But it also says that there are at least 100,000 “child-headed households” left — like the Nechavavas — to fend for themselves “We have an entire generation of children who are at extreme risk of abuse, of contracting HIV and a downward spiral of dropping out of school and taking their trauma into adulthood,” said James Elder, a Unicef spokesman in Zimbabwe.

It is not hard to see how the five siblings will end up. In the sanctuary of a Mbare church a 21-year-old man named Godknows told The Times how both his parents died of tuberculosis, and he had been living on the street for the past four years. He survived by breaking into cars and protecting prostitutes. “I am not ashamed because it’s the only way I can stay alive,” he said in a listless whisper. He looked sick.

In March in Mbare The Times met Tatenda Banda, a pretty 16-year-old orphan living in a rudimentary shelter. To survive she was selling herself to as many as half a dozen men a day for less than 30p a time. “I feel ashamed but there’s nothing else I can do,” she said then. “I’m afraid of Aids but there’s nothing to be done about it.” We tried to find Tatenda last week, but were told that she had died of Aids.

On the morning that The Times visited a Harare cemetery, 24 children had just been given a paupers’ burial. They now lie rotting in an unmarked mass grave.

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