Nearly half a million children around Lake Chad face "severe acute malnutrition" due to drought and a seven-year insurgency by militant group Boko Haram in north-eastern Nigeria, UNICEF said on Thursday.
According to a report by the United Nations' child agency, at least 49,000 children out of 475,000, are deemed to be at risk in Nigeria's Borno state. The agency said these children will die this year if they do not receive treatment which requires $308 million to cope with the crisis. Nigerian authorities declared a nutrition emergency in Borno in June 2016.
To date, UNICEF said it had only received $41 million, 13 percent of what it needs to help those affected in the four countries - Chad, Nigeria, Niger and Cameroon - that border Lake Chad.
In the beginning of 2015, Boko Haram gained control of swathes of territory around 50,000 square kilometres in and around Borno state, north-eastern Nigeria. However, military assaults by the four countries have pushed back the group in the last 18 months.
Most Boko Haram militants are now hiding in the wilderness of the vast Sambisa forest, southeast of the Borno provincial capital, Maiduguri.
UNICEF said that as Nigerian government forces captured and secured territory, aid officials were starting to piece together the scale of the humanitarian disaster left behind in the group's wake.
"Towns and villages are in ruins and communities have no access to basic services," UNICEF said in a report.
In Borno, nearly two thirds of hospitals and clinics had been partially or completely destroyed and three-quarters of water and sanitation facilities needed to be rehabilitated.
Despite the military gains, UNICEF said, 2.2 million people remain trapped in areas under the control of Boko Haram. Thousands of people are also staying in camps, fearful of going home.
Responding to its battlefield setbacks, Boko Haram has turned to suicide bombings, many involving children.
UNICEF said it had recorded 38 cases of child suicide bombings so far this year, against 44 in the whole of 2015 and just four the year before that.