Free trade policies backed by the UK government have caused a crisis in India leading thousands of farmers to commit suicide, a charity has said.
Christian Aid is calling for changes in UK laws
Christian Aid has examined the impact of market reforms in Ghana, Jamaica and India in a report.
It blames 4,000 suicides in India's Andhra Pradesh state on policies inspired by the IMF and World Bank.
The UK government says the criticism is "behind the times" and aid is not tied to conditions such as privatisation.
Christian Aid has urged the government to stop linking its aid to developing countries to free trade initiatives and wants the UK to use this year's presidency of the G8 to encourage change.
'Not free, not fair'
The report claimed western nations were backing free trade policies devised by the International Monetary Fund (IMF) and the World Bank, aiming at an end to barriers, tariffs and subsidies.
In Andhra Pradesh from 1999-2004, many farmers killed themselves because policies followed by the former state government resulted in increased debts.
In Jamaica, similar policies meant sugar cane production fell, driving women into prostitution and drug smuggling, it said. In Ghana legislation to protect farmers has been dented.
"Free trade today is not free and it's not fair for developing countries," said report co-author John McGhie.
"When rich countries ask poorer countries to open up their markets, they remove their protection from vulnerable industries.
"It's not a level playing field and poor people are the ones that suffer."
But Britain's minister for international development, Gareth Thomas, said: "Christian Aid seems to be behind the times, because our aid isn't tied to conditions such as privatisation."
He said the World Bank had agreed to review its terms after the government called on it and the IMF for a review.
The Department for International Development has said it is wrong to attribute blame for the deaths in Andhra Pradesh on the market reforms, citing repeated droughts and crop failures.
Some farming groups in India have also stopped short of blaming the deaths on liberal economic policies.
The chairman of the state's Federation of Farmers Associations said farmers would be able to cope with increased competitiveness if they had the proper institutional support.
But much of the support network for the farmers, including many government agencies, has been privatised and scaled down in recent years.