The UN Food and Agriculture Organization (FAO)and the World Food Programme (WFP) warned Wednesday that at least 10 million people in four southern African countries are threatened by potential famine - and that figure is expected to rise when reports from two other countries are completed. Reports published covering the results of recent joint missions to Malawi, Zimbabwe, Lesotho and Swaziland said that millions of people are on the brink of starvation, and that they will face grave food shortages as early as June, which would continue up to the next main harvest, in April 2003.