Northern Africa's Sahel region risks being plunged into a dramatic humanitarian crisis unless aid for those affected by drought, conflict and poverty is scaled up soon, three senior United Nations officials warned Tuesday.

The U.N.'s High Commissioner for Refugees, Antonio Guterres, said the situation in the 3,400-mile zone that stretches from the Atlantic to the Red Sea is suffering from lack of attention because of the conflict in Syria.

"We badly need to put this crisis on the map because its humanitarian dimension is becoming extremely, extremely dramatic," he told reporters in Geneva.

The region, which includes countries such as Mali, Chad and Niger has been hit hard by political instability and three droughts in less than 10 years. A U.N. appeal in December for $724 million to fund aid operations in the Sahel has elicited only half that amount so far, Guterres said.

UNICEF's Executive Director Anthony Lake said at least 1 million -- and possibly up to 1.5 million -- children in the region face acute, severe malnutrition, putting them at risk of death from starvation or disease. Of these, about 330,000 children are in Niger, some 208,000 are in northern Nigeria, 178,000 are in Mali and 127,000 are in Chad. The figures, which also cover Burkina Faso, Mauritania, northern Senegal and northern Cameroon, don't even include Sudan or South Sudan, where simmering conflicts are also stoking a humanitarian crisis.

"Someday there will be no excuse for looking back and saying why didn't we do more quickly," said Lake, who also shared the podium with the World Health Organization's Director-General Margaret Chan.

Unless donor countries provide more funds, "the result will be many children will die and many families will suffer," he said.

Chan said previous droughts in 2005 and 2010 meant many of the 15 million people affected by the crisis in the impoverished region have already sold off their reserves to survive, and aid needs to arrive by July at the latest.

"We are down to the last grain," she said.