More than 20 million people in the Horn of Africa need food aid because of two years of poor rainfall, the UN's World Food Programme (WFP) says.
The body says cuts in its funding have made it more difficult to feed people across Kenya, Somalia, Eritrea, Djibouti and Ethiopia.
The WFP is particularly concerned about Eritrea because it cannot get any reliable information about the country.
Some 14 million people in the region were said to need food aid last year.
The WFP says it cannot collect data from Eritrea because of movement restrictions and work permits not being issued.
It says it is concerned that malnourished children and pregnant women are not getting the help being offered across the rest of the region.
The Ethiopian government and WFP are using ports in Sudan and Somalia's breakaway region of Somaliland to increase the flow of relief supplies to the area.