The United Nations is warning that the famine in East Africa has not yet peaked and says Somali refugees are still pouring into Kenya despite efforts to alleviate famine conditions.

The U.N. humanitarian affairs office says that during the first week of August an average of 1,500 Somalis arrived each day at the Dadaab refugee camps in northern Kenya.

That number was up from July.

The U.N. deputy emergency relief coordinator, Catherine Bragg, said Wednesday that the world has not yet seen the peak of the crisis. She appealed to the international community for more than one billion dollars to help save lives.

The international famine relief effort appears to have gained momentum in recent days, as the militant group al-Shabab withdrew its forces from the Somali capital, Mogadishu.

Both the World Food Program and the U.N. refugee agency have conducted airlifts of emergency supplies to Mogadishu and are planning further flights to combat the regional drought, which has left 12 million people in need of urgent aid.

U.N. Secretary General Ban Ki-moon said at a conference in South Korea Wednesday that the Horn of Africa is facing a catastrophic combination of conflict, high food prices and drought. He urged the international community to deal with the underlying causes of famine and to focus on practical measures including drought-resistant seeds, rural infrastructure, and improvements in early warning systems.

The United Nations has declared five areas of southern Somalia famine zones and has warned the famine is likely to spread.

A U.N. report on Wednesday said the situation is growing worse in Somalia's neighbor, Djibouti. The United Nations says two-thirds of children under five screened in two northern regions were in need of therapeutic feeding.

The report said that proportionally, Djibouti is the second most affected country in the Horn of Africa.