Geneva - Growing violence by extremists has forced more than 1.5 million Nigerians to flee their homes and is deepening an already dire humanitarian situation in Nigeria, the UN warned Wednesday.
"Nigeria is without question of enormous concern," said Robert Piper, who coordinates the UN's humanitarian work in the Sahel region.
He said the violence wreaked by the militants of Boko Haram was "generating more and more suffering, it is generating more and more displacement."
Nigeria has in the past six months alone seen the number of people displaced inside the country soar from 600,000 to around 1.5 million, he said, quoting Nigerian government estimates.
In addition, some 100,000 Nigerians have fled across the borders to Cameroon and Niger, Piper told reporters in Geneva.
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That Nigerians see Niger, the world's poorest country, as a sanctuary "gives you a sense of what they must be fleeing from," Piper said.
More than 13,000 people have been killed since the insurgency began in 2009 and Boko Haram is now said to be in control of more than two dozen towns in its quest for a hardline Islamic state.
According to Nigeria's National Emergency Management Agency, 3.3 million people have been directly or indirectly impacted by the conflict in the northeast of the country.'Out of control'
"Our worry is that it will continue to spiral out of control with devastating consequences both for Nigeria itself and for the region," Piper said, adding that "the scale of the challenges there are truly very, very worrying indeed."
The fact that Nigeria produces half of west Africa's food makes the situation there all the more alarming, he said.
Taking a broader look, Piper said the entire Sahel region, which counts nine countries, Burkina Faso, Cameroon, Chad, Gambia, Mali, Mauritania, Niger, Nigeria and Senegal, has seen a dramatic increase in the number of people scrambling to put food on the table.
Just since the beginning of the year, the number of people considered food insecure has jumped from 20 to 25 million.
Across the region, 6.4 million children are acutely malnourished, Piper said, with around 600,000 children dying of causes linked to malnutrition each year.
The UN has appealed for $1.9 billion (1.5 billion euros) towards humanitarian aid to the Sahel in 2014, but has received just $1.1 billion of that.
The UN also said it had received just $12.3 million, or 13 percent, of the $93.4 million requested for humanitarian aid in Nigeria.