The United Nations says it is suspending aid to dangerous areas of Nigeria's northeastern Borno state after Boko Haram ambushed a humanitarian convoy.

The military and the U.N. Children's Fund say two soldiers and three civilians were wounded in Thursday's attack, including a UNICEF employee and a contractor for the International Organization for Migration. The convoy was traveling from the newly liberated city of Bama, where Doctors Without Borders has warned children die starvation daily with 15 percent suffering severe acute malnutrition and likely to die without food and medical aid.

Humanitarian workers say there is a "catastrophic humanitarian crisis" in the areas where aid is being suspended.

UNICEF spokeswoman Doune Porter says Friday that aid will continue to Maiduguri, a city of 1 million people hosting another million refugees.