The question of where the children were expected to go back to seemed to be lost on the municipality. It had come under pressure from local tourist businesses, whose owners had decided that the presence of hundreds of uncared-for kids on the streets ("chokoraa" as they're called derogatorily in east Africa) was putting off customers - and the kids simply had to go.

Many of the children reported being given 500 shillings (about 35p) and told to get a bus out of the area. Others said they were told by municipal officials to lie low for a while or to clean themselves up and try not to look like they were living rough. Most were held for between four and six weeks, after which they indeed went back where they came from - onto the streets again.

You don't have to stray far from the hotels and other tourist haunts to come across chokoraa during a trip to Tanzania. The scale of the problem might not compare with that in some other African countries, let alone in parts of Asia and south America, but it's there for anyone with eyes for more than the wildlife and the beaches. The same hungry, haunted faces, befuddled by solvent abuse and other cheap, anaesthetising highs, plead for handouts from the dollar-rich visitors. There are the same torn and tattered clothes; the same untreated wounds and illnesses; the same premature toughness and lack of laughter at an age that should know a lot less of the former and a lot more of the latter.

You can meet some of these children at the Tupendane drop-in centre in Arusha. (The name means "Let us love each other" in Kiswahili.) Workers there will tell you about girls as young as 10 or 11, who have already been initiated into a life of prostitution, and boys of a similar age, who have learnt to regard rape as a routine - and rapidly encountered - outcome of the lack of protection on the streets.

Here are children who have fled a life of abuse or neglect at home; children of drunken fathers who are either absent or violent; children who have lost one or both parents to AIDS; children of polygamous marriages whose fathers have abandoned one of their families; children of single parents who are simply too poor, too hard-pressed or too incapable to cope. Within a matter of weeks on the streets, or even days, according to those who work with them, they will have become brutalised to such an extent that they become the abusers themselves, initiating newcomers with the same cruelty and violence with which they were greeted only a little while before.

"It is hard to get people to care about these children," says Apolinary Masawe, director of the local Children for Children's Future (CCF) charity, which runs the Tupendane centre, "because often they care so little about themselves or each other."

Yet the recent story of northern Tanzania's street children is an optimistic one nonetheless. Because unlike so many other parts of the world facing a similar problem, here locals and outsiders together have acted effectively to begin to tackle it. Even the Arusha authorities' hard-nosed attempt to sweep the street kids under someone else's carpet has acted as a catalyst for more constructive action. From a peak of about 400 children on Arusha's streets a few years ago, the number is down to 100 or fewer today.

"I hesitate to say it, but we've almost got the problem under control," says Kate Macalpine, the English director of the Mkombozi Centre for Street Children, in nearby Moshi, which is acting as the lead agency for the Arusha Referral Service (ARA), a new consortium of groups working with street kids that is being established in Arusha.

ARA is the product of collaboration between Mkombozi and two Arusha-based initiatives. The first, and longest-standing, is CCF, which was founded by local residents concerned about the growing number of street children in 1994, becoming fully active in 1998. The other, Friends of Kids, was set up in 2000 by four people working for the UN's International Criminal Tribunal on Rwanda, which operates from Arusha. It started as a simple lunch project, providing meals for about 30 street children, but rapidly found itself being drawn deeper and deeper into longer-term issues such as health care and education.

This drew it into close collaboration with CCF, whose nurse attends its meals sessions, held four times weekly at a local church. As well as the Tupendane drop-in centre, which can cater for up to 50 short-stay residents at a time, CCF runs a longer-term residential centre outside Arusha, which is currently home to 50 boys and eight girls. (There are far fewer girls among the street kids because they find it easier to get employment as "housegirls" or to be given a place to live by relatives who value their help around the home.)

Although the Tupendane centre is open at any time to street children, who can call in whenever they want to see a teacher or social worker or to seek medical attention from the nurse, the aim is to get those who come to it off the streets rather than supporting them in such a vulnerable way of life. There is a rough time limit, therefore, of about four months on the children's involvement with the centre. This period is spent in intensive counselling; literacy courses and other educational programmes; and a range of sports and cultural activities, including football, theatre and even acrobatics.

"We try to get to the root of their problems, and to find out what they would like to do with their lives," says Apolinary Masawe. "Most of them say they don't know to begin with. They have no idea that they could be something - even to be a taxi-driver or a tour guide is outside their ambitions for themselves."

Above all, like the Mkombozi project, CCF concentrates on trying to bring families back together - reuniting the children with one or both of their parents, if possible; or finding members of their extended families who will take them in, if not. The workers involved with both projects devote a great deal of time to tracking down and visiting relatives, finding out what problems they are facing that might make it difficult for them to take on the children, and trying to help them with advice and other assistance.

Only as a last resort does CCF move children to its long-term residential home. Apolinary Masawe estimates that his organisation has reunited around 150 street children with their families in the past four years; as well those currently housed in its residential projects, a further 18 have been placed in boarding schools.

"It's actually very rare that these kids have no family at all," says Kate Macalpine. "The extended family is very strong in east Africa - it's just that family members often don't know what's happening to these children or have lost contact with them. The logistics of tracking them down and assisting them to take responsibility for the children are enormously difficult and very expensive. Institutional care is a lot cheaper."

Mkombozi has dealt with about 2,000 children since it was set up as a small feeding programme, which gradually expanded into a full-scale rehabilitation project, in 1997. "There is a very mobile population of street kids in Moshi, with 60 per cent of them coming from rural areas," says Kate Macalpine. "We aim to reach the new kids within 24 hours, before the real damage is done."

Shermin Moledina, the Friends of Kids coordinator, says that, "Once the kids have become hardened to life on the streets, it becomes much more difficult to help them. Their problems multiply and they become much more resistant to help. That's why it's so important to reach them quickly." The staff and volunteers of the different projects are on constant look-out for new arrivals, going out to talk to them on the streets and making sure that help is made available to them.

"The pressures that lead to children ending up on the streets are the same the world over," says Kate Macalpine. "Family breakdown, poverty, peer pressure, school exclusions - which are especially important here as a result of families being unable to afford school fees or uniforms." The "really scary thing", she believes, is the size of the at-risk population, which Mkombozi estimates at 30-40 per cent of all children in the area, such is the scale of the poverty and other problems facing the region.

"The difference between a family that can cope and one that can't can be very fine indeed," she says. "It takes intensive, high-quality intervention to make that difference, and of course that's expensive. But we've seen that it works, and we've seen the cost of not making that intervention elsewhere in the world."