Most of the one million deaths caused by Malaria each year occur in Africa, where the disease costs the continent $12 billion a year, the World Health Organization said Monday.

WHO southern Africa regional director Antoine Kabore told delegates at African malaria day - held in Zambia this year - that the disease is slowing development on the continent because it affects productive workers.

“Malaria remains a major contributor to the disease burden in Africa.

About 60 percent of the estimated 350-500 million global clinical malaria episodes and over 80 percent of the over one million deaths globally each year occur in Africa,” he said.

Senior Zambian officials and delegates from the United States, Europe and the rest of the continent attended the normally festive annual celebration. It was toned down to speeches in the capital as Zambia had declared a national day of mourning for the 51 people killed in a mine blast last week.

“The burden on health systems, absenteeism among school children and diminished or lost worker productivity, all contribute to make malaria a significant contributor to low economic growth in endemic countries, estimated at costing African countries about $12 billion,” Kabore said.

Sunday the World Bank announced in Washington it would expand its fight against Malaria because global efforts in the past five years had failed. Between $500 million and $1 billion were needed over the coming five years, it said.

David Brandling-Bennett, a senior program officer at the Bill & Melinda Gates Foundation, told Reuters the charity would scale up its assistance to fighting malaria in Africa.

Interventions through the Foundation’s $500 million budget for 2005 aimed at supporting health care in impoverished regions of the world, including Africa, will be directed mainly at pregnant women and children under the age of five, he said.

“The number of cases and deaths has gone up in recent years due to a number of factors, including the fact that we now have widespread resistance to drugs,” he said.

The Bill & Melinda Gates Foundation is now supporting efforts by the United Nations Children’s Fund (UNICEF), WHO, some international donor agencies and the World Bank to develop new drugs, Brandling-Bennett added.

“The development of new drugs is really expensive and not attractive to the big pharmaceutical companies because people with Malaria cannot afford to buy the drugs and so there is not a profit there for the companies,” he said.

Brandling-Bennett said the foundation is also investing in malaria vaccines to protect children and pregnant women against the disease.