Updated

Nearly half a million children in areas affected by Nigeria's Boko Haram insurgency could suffer from severe acute malnutrition this year, a figure that has more than doubled since the beginning of the year, the United Nations children's agency said Thursday.

Years of conflict have aggravated malnutrition in a region that was already one of the poorest in the world. In Nigeria's northeastern Borno state, 49,000 children "will die if they do not receive treatment," the agency, known as UNICEF, said in a report.

"The Lake Chad crisis is a children's crisis that should rank high on the global migration and displacement agenda," said Manuel Fontaine, UNICEF Regional Director for West and Central Africa. "Humanitarian needs are outpacing the response, especially now that new areas previously unreachable in northeast Nigeria become accessible."

Boko Haram's seven-year insurgency has killed more than 20,000 people and displaced more than 2.6 million in Nigeria and neighboring Cameroon, Niger and Chad, where the extremists have extended attacks in recent years.

An additional 2.2 million people, over half of them children, are feared to be trapped in areas under the control of Boko Haram, the U.N. said.

The agency said it has received just 13 percent of the $308 million needed to help families affected by violence in the region.

The countries surrounding Lake Chad are all contributing to a multinational force to combat Boko Haram, making recent gains against the insurgents who pledged allegiance to the Islamic State group last year.