Thousands of discarded computers from Western Europe and the United States arrive in the ports of west Africa every day, ending up in massive toxic dumps where children burn and pull them apart to extract metals for cash.

A technician at a Kenyan non-governmental organization carries a computer monitor to be converted into a television set in Nairobi in this file photo. Computer for Schools Kenya has been rehabilitating donated computers since 2002 but opted to convert old monitors into television sets to reduce the huge amount of toxic electronic waste being generated.

The dumping of the developed world's electronic trash, or e-waste, is in direct contravention of international legislation and is causing serious health problems for inhabitants of the shanty towns that have sprung up amid the smoldering dumps in Lagos and Accra.

Campaigners believe unscrupulous scrap merchants are illegally dumping millions of tons of dangerous waste on the developing world under the guise of exporting it for use in schools and hospitals. They are calling for better policing of the ban on exports of e-waste, which can release lead, mercury and other dangerous chemicals.

"Ghana is increasingly becoming a dumping ground for waste from Europe and the US," said Mike Anane, director of the League of Environmental Journalists in Ghana.

"The people that break open these monitors tell me that they suffer from nausea, headaches and respiratory problems."

More than half a million computers arrive in Lagos every month but only about one in four works. The rest are sold as scrap, smashed up and burned.

"Millions of tons of e-waste disappear from the developed world every year and continue to reappear in developing countries, despite international bans," said Luke Upchurch from Consumers International, which represents more than 220 consumer groups in 115 countries.