At least 10 million people face starvation in four southern African countries unless the international community acts swiftly, UN aid agencies have warned.

We have to get the message out to donors - a famine can be averted if they act quickly

WFP regional director Judith Lewis

A report jointly compiled by the UN World Food Programme and the Food and Agriculture Organisation - one of the most comprehensive to date of the crisis - said that famine in Malawi, Zimbabwe, Lesotho and Swaziland is not yet widespread, but warned that urgent action is needed in order to avert a humanitarian crisis.

It added that once information is completed from two other southern African countries - Zambia and Mozambique - the situation would appear "even bleaker".

There are several reasons, the report states, for the current crisis, including drought, economic policies and, in Zimbabwe, the disruption of farming due to the government's controversial land reform programme.

The price of maize - southern Africa's staple food - has also soared due to drought affecting the crop in countries such as Malawi.

Situation urgent

Both agencies have called on international donors to provide supplies, estimating that southern Africa will have to import almost 4 million tonnes of food over the next year if it is to meet the needs of its population.

The WFP has estimated that the cost of such an international aid operation would be around $400 million, Reuters news agency reported.

"We have to get the message out to donors - a famine can be averted if they act quickly," Judith Lewis, WFP's regional director for southern and eastern Africa, told Reuters.

"Much needs to be done, and we need to do it now."

The crisis has been made worse by the high rate of HIV and Aids in the region, which has weakened the local population's resistance to disease and left them more susceptible to famine.

In addition, climatologists have warned that El Nino, a periodic warming of part of the Pacific Ocean, may well return this year, which could in turn lead to yet more floods and drought in the stricken region.