Johannesburg, South Africa ? Drought combined with deepening poverty, a runaway AIDS crisis and economic mismanagement have put more than 12 million southern Africans at risk for starvation and could kill 300,000 in the next six months unless Western donors respond quickly, the United Nations warned Thursday.

Half of those endangered live in Zimbabwe, once a major African food producer but now a nation embroiled in political crisis, including a bitterly controversial land redistribution effort that is forcing the country’s white farmers from their fields even as shops run short of staple cornmeal.

Sifiso, left, and Rose are abandoned HIV-positive babies at the Cotlands home in Johannesburg, South Africa. About 28 million of the 40 million people infected with AIDS live in sub-Saharan Africa, according to a U.N. report, and the numbers show no signs of abating.

Southern Africa has long had cycles of drought and hunger, but a deadly new combination of risk factors means six southern African countriesZimbabwe, Zambia, Malawi, Mozambique, Lesotho and Swazilandare now facing “the most serious humanitarian crisis taking place in the world today,” James Morris, head of the U.N. World Food Program, said Thursday in Johannesburg.

The agency is appealing for $507 million in emergency funding to more than triple its disaster relief efforts in the region, after harvests during the last several months failed to produce enough grain to tide the countries through the coming year.

Unusual circumstances

While wars and other political crises have contributed to past famines in Africa, the emerging food shortage in southern African is unusual both because it comes in what had been an important food-producing zone and, more importantly, because factors beyond the weather have played a particularly strong role.

The region has the highest AIDS infection rate in the world, and AIDS deaths have robbed farming communities of workers and left behind tens of thousands of orphans unable to feed themselves. Poverty is growing, in part because of the AIDS crisis, and millions were surviving on the verge of malnourishment even before a two-year drought dried up fields in much of the region and other areas were hit with unusual floods or frosts.

Race politics, economy

Political and economic mismanagement have contributed to the deepening crisis. In Zimbabwe, President Robert Mugabe has ordered the country’s white farmers, who run many of the nation’s largest and most productive farms, to abandon crops in the fields and prepare to leave their farms altogether by Aug. 10 as part of a political effort to transfer the land to black owners.

Mugabe also has fixed grocery store prices on staple foods at a level below production costs, distributors charge, leading to large-scale shortages.

The World Food Program, which once purchased a healthy share of its African relief grain from Zimbabwe, has had to close its procurement office in the country and instead open a food aid distribution center, Morris said. The agency, oddly enough, is now buying some of its food intended for southern Africa from formerly famine-struck Ethiopia.

Because of the political dimension to the emerging food crisis, the problem is expected to linger beyond next year’s harvest, the U.N. official said.

In a region wracked by AIDS, malaria, tuberculosis and other health issues, aid workers have had difficulty pinning down a number of famine deaths, as most of those dying are succumbing from a variety of problems worsened by malnutrition.

But UN World Health Organization officials say 300,000 people in southern Africa could die in the next six months without stepped up international intervention, including programs to improve access to medicine, vaccines and clean drinking water as well as to a supply of food.