Ian Berry, one eight photographers who were asked to explore the theme of contemporary global slavery, focused on the impact in Ghana of unfair trade rules.
With some 70 per cent of Ghana dependent on agriculture, Christian Aid said livelihoods had been "ruined" in recent years by donor governments and international financial institutions making aid and trade conditional on trade liberalisation.
"The enforced removal of protective tariffs has left local producers unable to compete with the flood of cheap foreign imports, particularly of tomato paste, rice and poultry," the development agency said.
The exhibition, Disposable People, which is showing at the South Bank Centre in London until November 9, shows how people have been reduced to slave-like conditions as a result.
Berry travelled from the rice growing region of Dowena in the south to the tomato growing farms in Ashanti region before heading to the poultry farms in the centre of Ghana and the stone quarries in the west of the country.
Everywhere he went farmers, traders and labourers spoke of hardship.
"I used to own a tomato farm but I couldn't feed my family," said Kofi Eliasa, who was unable to make a living once cheaper European tomato imports appeared.
He now works a 12 hour day breaking stones in a quarry for less than £1 a day.
One of Berry's shots shows a large advertisement for an imported tomato brand covering the wall of a local market.
Alex Cobham, Christian Aid's policy manager, said: "Based on a doctrinaire belief that 'free trade' is always an engine of growth, rich countries and the IMF and World Bank have forced liberalisation on economies that are not strong enough to cope.
"The impact has been devastating. Foreign goods, often subsidised in the country of origin, have undercut local producers, causing extreme hardship. The livings of farmers like Eliasa have been decimated.
"Developing countries should not be forced to sign away their economic policies but should be allowed to liberalise at a pace they can adjust to."
According to UN estimates, developing countries lose $1.3bn every day due to unfair trade rules. Christian Aid believes that trade justice is the best chance for poor countries to combat poverty.
Other aspects of modern-day slavery explored in Disposable People include child labour in Bangladesh, chattel slavery in Sudan, people trafficking from Eastern Europe, and the story of South Korean women held as sex slaves by the Japanese in World War II who are still seeking restitution.
About the exhibition:
The exhibition is open from 10am - 11pm daily at The Clore Ballroom, The Royal Festival Hall. Admission is free. After the London showing, Disposable People will tour England and Wales for fourteen months and be shown in venues from Plymouth to Newcastle.
For more on Christian Aid's Trade Justice Campaign visit www.christian-aid.org.uk
