These 'refugees' are in Tuen Mun and the experience is a simulation carried out by Crossroads International, a charity that provides donated goods, either from individuals or companies, to those in need in Hong Kong and to about 100 countries around the world. It happens to be Afghanistan, but it could be Bosnia, Uganda or Darfur.

Founders Sally and Malcolm Begbie, accountants originally from Australia who previously ran their own businesses, have seen many people who have fled their homelands or have been born into and trapped by poverty. So the simulation - a 24-hour slum survivor course co-organised by the Begbies' son, David - is based on cold reality.

Business leaders working in Hong Kong, bankers, lawyers, a carpenter and Dick van der Tak, chief executive of NGO Medecins Sans Frontieres Hong Kong were all taking part in the course last weekend.

Twenty-four hours to get a small taste of what it feels like to either be stripped of everything you own and people you love, or to be born into a slum where your chances of survival are immediately cut by high infant mortality, poor sanitation, disease, and lack of money, where, even if you're an Einstein, no one is likely to find out, as education is a luxury beyond reach.

Not everyone's idea of a fun day out.

But last year, 5,000 people attended courses at Crossroads, some of which are as short as 90 minutes, with many schools and businesses among them. This month alone, there have been 1,000 people, says David Begbie. Most of those taking part last weekend had garnered thousands of dollars in sponsorship.

'The noise was physically very disorientating,' Martin Wheatley, chief executive of the Securities and Futures Commission, said of the start of the course, for which he was a refugee caught in a war zone. 'It was also not knowing who was friend or foe among the soldiers and the teachers, or whether they were just interested in extortion.' Mr Wheatley was joined by his wife, Magda, and two daughters, with 10-year-old Gabriela remarking that she was 'very scared'.

Each participant was given a name, a family, and a role. Some were 'wounded'. The women wore headscarves.

Hannah Wheatley, 13, was less scared and more fascinated. 'I thought it was all really interesting, also being a woman and only being allowed to talk to your family and not any other men. I'm 14 in this and I'm supposed to be betrothed to someone.'

Participants were stripped of their watches, wedding rings, anything the 'soldiers' could sell.

Initially expecting to be part of the media, I was 19-year-old Annemarie Tula, single, a student, wounded in the leg.

So the imagination starts working. I know it's Tuen Mun, but will I get food? Will I be interrogated? If this were real, would I be at risk of rape?

The participants were eventually led by United Nations forces around the Crossroads complex in the dark, through enemy territory, and, finally, to a safe field, where they built shacks for the night - 2-metre by 2-metre wooden homes with corrugated iron roofs.

'I found I was completely unable to be my normal, assertive self,' Ben George, of St Paul's Co-Educational College, said of his refugee experience. His job usually involves making decisions while taking children on activities such as mountaineering to benefit their social and moral education.

'Your comfort zone was gone, there were no cues here, it was difficult to work out what to do. When I was interrogated, I didn't know how far they would go.'

Steve Clinefelter, president of California Fitness, also experienced interrogation.

'I think it gives the opportunity for your imagination to capture what it might be like. But, of course, the reality is even worse - the mind games and the element of surprise. It's quite unnerving. Everything you have taken for granted is off the table.'

Another participant, Fred Armentrout, communications director at the American Chamber of Commerce, said: 'We're only doing 24 hours, but you're confronted with the reality of how many people have to struggle for survival.'

Food that evening consisted of a bowl of dahl, eaten with fingers. Then an uncomfortable night's 'sleep' on the ground with just a mat and blanket. Need a pillow? Use your boots.

Mr van der Tak is familiar with refugee camps and slums and, like Mr Armentrout, who has visited slums in the Philippines and elsewhere, joined the course to see how real it is. He speaks of the ongoing stress experienced by refugees in the camps where he worked.

'Even when you tell them repeatedly that they are now safe, they are unable to accept it. Every night when it gets dark, they expect the knock at the door.'

The second day is a lesson in how 3 billion people live on less than US$2 a day, how children in slums in Cambodia, Bangladesh, India and Sri Lanka are paid HK$2.40 to produce 200 bags.

In one exercise, the participants in Tuen Mun, still working in the families that had been formed the day before, each have to produce paper bags out of newspaper and glue made with flour and water. Each 10 minutes of bag-making on the ground outside the shacks constitutes a week of labour. In that time, the family have to raise 100 rupees (HK$18) for land rent for their shack, and 180 rupees for food.

Hong Kong bankers, lawyers, a financial adviser, the head of California Fitness, all kneel on the ground, feverishly tearing paper, folding it, gluing it, before one member of the family runs to the shopkeeper to get a good deal for their bags, hoping to make enough for their rent and food. No one gets anywhere near the required amount.

The next week - or 10 minutes - begins with one family losing their shack because they are unable to raise the rent. They are forced to live with 'Mr Deepadet' in an area of the field called 'Under the Bridge'.

'I was completely oblivious to the other families,' Mrs Wheatley says. 'There was no time to give my daughter care and attention, I just had to make enough to survive.'

A frustrated Tim Smith, managing director of Maersk in Hong Kong, says: 'It just got worse and worse with Mr Deepadet. We made 20 bags, they said we made eight. We would never get out of debt.'

David Begbie explains: 'In just 29 minutes, you can see the seeds of frustration growing. All of you are stuck in poverty. There are probably Einsteins in slums who never get the chance to shine. There are 216 million children between the ages of five and 17 who are working around the world.

'I hope there is empathy [among participants], obviously. But I hope they also see that poverty is not just an issue for large NGOs, but also for the housewife or small business.

'There is a place to contribute if the desire is there. Both Kofi Annan and the current United Nations secretary-general, Ban Ki-moon, have said that poverty is too big a problem for individual governments. What is needed is for private businesses and individuals to pool together.'