The United Nations says “massive” action is needed to save millions of people living in the Horn of African from starvation. And it announced that it will begin an airlift of food aid into the Somali capital, Mogadishu, as well as eastern Ethiopia and northern Kenya on Tuesday.

The U.N. World Food Program held an emergency meeting on Monday in Rome, where its chief, Jacques Diouf, described as “catastrophic” the situation facing the region in the midst of the worst drought in 60 years.

A donors conference will be held in Nairobi, Kenya, on Wednesday, when the WFP will seek pledges of $1.6 billion in aid for the more than 11 million malnourished, many of them children.

In Somalia, which one official described as the “epicenter of the famine,” around a third of the population is facing starvation.

The official said that in Somalia there are soaring levels of malnutrition. She described desperate mothers forced to abandon their children along roadsides as they traveled to refugee camps in neighboring Kenya.

The access of international aid organizations to areas of southern Somalia has been hampered by militants of the al-Qaida-linked militant group al-Shabab, which controls much of the region. Denying there is a famine, the Islamist militants have regularly threatened relief groups.