The United Nations has declared famine in five areas in war-wracked Somalia, while millions are struggling for survival in parts of Ethiopia, Djibouti, Kenya and Uganda due to the region's worst drought for decades.
African Union Commission chief Jean Ping urged Africans to "act out against hunger by providing both cash and in-kind support for urgent life-saving assistance to our brothers and sisters in the Horn of Africa."
A total of $2.4 billion (1.6 billion euros) is required to assist the 12.4 million drought victims. The AU has pledged $500,000.
A pan-African fundraising campaign, Africans Act 4 Africa, has criticised African governments and the AU for not responding quickly enough to the crisis.
So far, African governments have pledged $21 million, but only from a few countries, the fundraising group said in a statement, adding that Africa should offer a minimum of $50 million.
"If we truly believe in 'African solutions for African problems' we need to demonstrate this very clearly not just in words but in actions," the group said.
"We need to ensure this is not just another talk shop where AU leaders spend a lot of money on travel, protocol and their entourages."
European Union foreign affairs chief Catherine Ashton on Wenesday urged world governments to meet a "moral obligation" and increase emergency aid to the drought-hit Horn of Africa.
"The situation is grave, and it is a moral obligation of the international community to offer its help," she said.
Ashton said the EU's immediate humanitarian commitment for this year had risen from 97 million euros to 158 million, while national aid pledges from its member states totalled a further 440 million.
The drought, caused by two years of failed or inadequate rains, has wrecked livelihoods, forced hundreds of thousands to flee their homes, wiped out livestock and decimated crops.
Somalia has been the worst affected country in the region, with hundreds of thousands of people forced to seek help in crowded camps in neighbouring Ethiopia and Kenya.
UN Humanitarian Coordinator for Somalia Mark Bowden said Somalia's Middle and Lower Juba regions could be hit by famine, adding to five other regions already declared to be in famine by the UN.
"We are anticipating that two more areas of southern Somalia will be included," Bowden told AFP.
AU representative to Somalia and former Ghanaian president, Jerry Rawlings, as well as the deputy secretary general of the United Nations, Asha Rose Migiro are expected to attend the Addis Ababa conference.
Also expected to attend are leaders of African economic blocs and heads of state from East Africa's Intergovernmental Authority on Development, which includes Ethiopia, Djibouti, Kenya, Somalia, Sudan and Uganda.
Copyright AFP (Agence France-Presse), 2011