The humanitarian crisis triggered by Boko Haram's "violent and inhuman campaign" is worsening, with 10.7 million people in need of aid in northeast Nigeria and parts of Cameroon, Chad and Niger, the U.N. humanitarian chief said Thursday.

Stephen O'Brien told the U.N. Security Council that although Boko Haram has lost much of the territory it once controlled as a result of military campaigns in the region, its raids and suicide bombings targeting civilians are still causing widespread death and destruction in those four countries which comprise the Lake Chad Basin.

Over the past 12 months, he said, the crisis has grown "in dramatic fashion," with the number of people needing humanitarian help, rising from about nine million in July.

Britain's U.N. Ambassador Matthew Rycroft urged the Security Council to visit the Lake Chad Basin region in the coming weeks to shine a spotlight on the depth of the crisis, stressing that it is not only humanitarian but also about politics, development and "countering terrorism."

"What started as a protection crisis," O'Brien said, "has become also a major food and nutrition crisis - today one of the largest humanitarian crises in the world."

He said a year ago, three million people across the Lake Chad Basin were "severely food insecure," meaning they had very little to eat and needed assistance. "Today there are 7.1 million," despite the response of the U.N. and its partners, he said.

In addition, some 2.4 million people are displaced, including 1.4 million children, O'Brien said. And in northeast Nigeria alone "over 7,000 women and girls have been subjected to Boko Haram-related violence."

He urged stepped-up donations to help the millions in need saying the 2016 U.N. appeal received $238 million - just 49 percent of what was needed - and the 2017 appeal will be $1.5 billion, reflecting the deteriorating situation in the region.

Assistant Secretary-General for Political Affairs Taye-Brook Zerihoun told the Security Council that the region suffers "from the combined effects of violent extremism, and a serious humanitarian crisis as well as human rights abuses and violations by terrorist elements and counter-terrorism measures."

Despite "the commendable military efforts by the region against Boko Haram," he said the ongoing violence has destroyed lives, livestock and food stocks and paralyzed local economies. The economic impact is estimated at about $9 billion in northeast Nigeria alone, he said.

Zerihoun warned that "a military approach will not bring an end to Boko Haram."

"Affected countries must simultaneously tackle the humanitarian consequences as well as the root causes that led to the emergence of the group," he said. "Military operations should be followed with stabilization measures, the restoration of state authority and addressing the social, economic and political grievances of marginalized communities."

AP