LAGOS, Nigeria (AP) — Doctors Without Borders says thousands of children have died of starvation and disease in Boko Haram-ravaged northeastern Nigeria, quoting a new survey that has brought Nigerian officials to stop denying the crisis.

Emergency program manager Natalie Roberts says a survey of two refugee camps in northeastern Maiduguri shows that a quarter of the expected population under-5 children is missing, assumed dead.

Doctors Without Borders first sounded the alarm in June but Nigerian camp officials as late as September denied any child was suffering malnutrition.

Roberts says the organization hopes that official recognition of the calamity in which "thousands are dying every day" will help bring urgently needed aid before older children also start to succumb.

The crisis is aggravated by alleged theft of food aid being investigated by Nigeria's senate.