Jean Ping called on AU member states in particular to give as much as possible to help Somalia and other drought-hit countries.

He said Africa ran the risk of famine spreading across the Sahel, the broad swathe of semi-arid land stretching across the continent south of the Sahara.

"We need to participate (in the fundraising effort) to show the rest of the world that we are also capable of resolving African problems with African solutions," he said at the opening ceremony of a summit of southern African leaders in Angola.

The August 25 donor conference in Addis Ababa will call for funds to help the estimated 12 million people in danger of starvation in the Horn of Africa.

Ping said the AU had dispatched former Ghanaian president Jerry Rawlings on a tour of African capitals to lobby for donations, noting that Algeria had already promised $10 million.

He said the meeting was urgent given that "the countries of the Sahel will rapidly be affected by famine" as well.

"Even AU member countries classified as poor should make their contribution, in cash or in kind, even if symbolic," he added.

He also made a special appeal to the "BRICS" group of emerging economies -- Brazil, Russia, India, China and South Africa -- to make significant donations.

He called the conference the first AU effort of its kind, and said it needed to set a precedent.

"If this conference is not a success, it will be difficult for us to organise a similar one," he said.

The AU has come in for criticism for postponing the conference from August 9.

Imtiaz Sooliman, chairman of South African aid group Gift of the Givers Foundation, said last week the AU had been "very slow" in responding to the crisis.

"If Africa doesn't care about Africa, how do you expect other countries and other continents to care about this continent?" he said.

"The stark fact is that in southern Somalia the situation is deteriorating by the day," Andrew Mitchell, Britain's international development secretary, said in Nairobi following a visit to Mogadishu.

Up to 400,000 children are at risk of death through starvation if urgent action is not taken now, he added, announcing a $41 million (29 million euro) funding boost.

Without an "urgent response" the crisis could become as bad as Somalia's 1991-2 famine, when over 200,000 people lost their lives, warned Mitchell, who visited feeding centres and camps for those fleeing extreme drought.

"This is a race against time," he warned.

Britain's funding boost -- to be channelled through the UN children's agency -- includes two months supplementary rations for up to 192,000 people, and measles vaccinations for at least 800,000 children.

It will also provide $4 million for agricultural projects, including the vaccination of livestock.

Over 12 million people in parts of Djibouti, Ethiopia, Kenya, Somalia and Uganda are in danger of starvation in the wake of the region's worst drought in decades.

War-wracked Somalia is the country hardest hit by the Horn of Africa drought, with five areas declared to be experiencing famine, much of those under the control of the Islamist Shebab militia.

"Evidence of malnutrition is not just in the camps and feeding centres but on every street corner," Mitchell said.

"We risk seeing a whole generation of people decimated by starvation and disease, and further instability across the region," he added.

Mitchell explained that the recent Shebab withdrawal from the capital Mogadishu had not allowed the widening of aid delivery to the areas abandoned by the rebels.

"It is clear that with the Shebab withdrawing, there is an opportunity for the transitional government to first of all stabilise its position in Mogadishu," he told reporters in Nairobi.

"The withdrawal of the Shebab does not make it necessarily easier for humanitarian and relief agencies. It is difficult for them to operate in ungoverned space."