"Leaded gasoline is still widely used in Africa," Rob de Jong, programme officer with UNEP, told Reuters. "What is needed in Africa is awareness that unleaded is better for you, better for the environment and better for the vehicle," he said.

UNEP warned that lead emissions released with exhaust fumes lead to many ailments including respiratory problems, saying that children are the most vulnerable.

The heavy metal contaminates the air and pollutes engines, raising vehicle maintenance costs.

About 90 percent of the world's petrol supplies are unleaded, but the remaining 10 percent is made up of leaded fuel found mainly in Africa and some countries in Asia and Latin America, the report said.

UNEP blamed Africa's slowness to switch to unleaded fuel mainly on outdated technology, but said a lack of awareness of the health risks and misconceptions about the impact of unleaded fuels on the engines had also played a part.

Only four African countries, Egypt, Libya, Mauritius and Sudan, are already fully lead free. Morocco, Reunion, Tunisia and Western Sahara will join them this year.

UNEP said that more than 20 African countries, including Eritrea, Ghana, Kenya, Nigeria, South Africa, Togo and Uganda, had drawn up or were in the process of making plans to phase out leaded petrol by 2005-2006.

UNEP hopes up to 100 environment ministers will attend the five-day conference at its Nairobi headquarters, which opened this week, to discuss how to implement resolutions from the Johannesburg World Summit on Sustainable Development in September.