A group of doctors warned last week that if climate change is not effectively tackled we all face a health catastrophe. What they did not say is that the catastrophe is already here for millions of the world’s poorest people, because when they get sick, or even have a baby, they cannot afford the medical bills. A new mother who has to undergo an emergency caesarean section in Sierra Leone can expect to be presented with a bill of up to £175 –three times higher than the average annual salary. Her family then risks slipping into even deeper poverty than it is in already.

This week, at the UN General Assembly, Britain’s prime minister Gordon Brown is to lead a new push to scrap fees for essential health care in seven poor countries, a move that could end farcical situations such as this.

Making patients pay for healthcare was introduced in poor countries in the 1980s, often as a condition of attracting lending from the World Bank and the International Monetary Fund, but the fees have rarely contributed to more than 5% of a country’s running costs for health services.

The fees, however, are extremely effective in keeping people away from hospitals, clinics, and doctors. In our experience, charging as little as 50 pence deters patients from seeking care, with serious consequences. Children with fever aren’t taken to the doctor and, instead of being diagnosed and treated early, come to our free clinics with severe pneumonia, often too late to be saved.  That is hardly in line with the real needs of the population. It has been estimated that if fees had been abolished in 2000, when the UN Millennium Development Goals to fight poverty and to improve health care were introduced, more than 2.5 million children’s lives would have been saved by now.

Removal of user fees is a welcome step but in isolation it is not enough. In some countries where fees have been abolished the number of patients seeking care has increased fivefold, when there are not the extra numbers of doctors and nurses to cope. Ending fees must be accompanied by extra funding and technical assistance to support and train more health workers and supply drugs and equipment and make free healthcare policy a reality.

That is the commitment that world leaders can pledge this week: to get the money through – and develop the technical assistance – and not let it become a feel-good promise with no concrete result. Mozambique has been planning to abolish fees but no donor country has come forward to provide the needed £8 million a year, which is 10 per cent of its current health budget.

The evidence for scrapping fees is compelling. In Sierra Leone, one year after we abolished flat fees for patients, our doctors diagnosed and treated 10 times more children with malaria. In contrast, Burundi introduced fees in 2002, and two years later a survey showed that four out of five patients had gone into debt or had been forced to sell food they had grown for themselves in order to pay the bills. Patients who failed to pay risked being imprisoned by clinics or having their identity papers confiscated.  Since then, Burundi has implemented free care for children and maternal deliveries. The positive impact on use of health services is patently clear.

This week, world leaders at the UN must go beyond simply making a laudable public commitment at a high-profile meeting and actually direct the necessary money to all the right places and make a major difference to the lives of millions of people cut off from essential care.

Tejshri Shah is head of Médecins Sans Frontières UK’s Manson Unit, which provides direct medical support to Médecins Sans Frontières teams in the field.