The UN World Food Programme has appealed for urgent donations of more than $150m (£85m) to prevent a food crisis in southern Africa.
Malawi has already declared a national disaster over the crisis
It warned that almost 10 million people in six countries - Zambia, Zimbabwe, Malawi, Mozambique, Lesotho and Swaziland - urgently needed food aid.
The shortages are blamed on drought, HIV/Aids and chronic poverty.
The appeal came as Zimbabwe said for the first time that land seizures since 2000 had contributed to shortages.
The BBC's Hilary Andersson in southern Africa says that the situation in Zimbabwe has been compounded by the collapse of the economy.
Children in rural areas of the country have already started to show signs of malnutrition, she says, with some eating only once a day.
The WFP said it was well short of the $400m needed to help feed people in the six countries before the harvest next April.
Many of the people affected would die unless the money was provided, it said.
"The children of southern Africa need help now - before their tiny emaciated bodies appear on television screens," said the programme's southern Africa director, Mike Sackett.
"People are struggling to survive and the harshest months are still ahead ... It is tragic that there is so much wealth in the world but so little of it is ever shared," he added.
The US is the biggest donor so far, with more than $100m, while the EU has provided $64m.
But Mr Sackett said no money had been pledged by oil-rich nations despite record high oil prices this year, and the WFP was now lobbying Gulf states from an office in Dubai.
Zimbabwe was the worst-affected area, with 4.3 million people in need of help, a WFP statement said.
Our correspondent says food prices are escalating wildly, new farmers have failed to grow sufficient food and 700,000 people have been ousted from their homes as part of President Mugabe's urban clean-up programme.
Zimbabwe's government has frustrated the delivery of large quantities of foreign aid, she adds.
Church leaders, meanwhile, are warning that government food is being given to supporters of President Mugabe's party, Zanu-PF and not to his opponents.
"President Mugabe is deliberately starving his people. They are doing this for political motivation," Bulawayo Archbishop Pius Ncube told the BBC.
"Break the people of Zimbabwe until they completely agree that Mugabe is the only master of Zimbabwe and they must all support Zanu-PF or starve."
Mr Mugabe's government has always in the past blamed the food shortages largely on the lack of rain.