Future leaders of the country resident in the North East do not have access to food, water and health care.
According to the United Nations, aid agencies have just 18 months to deal with the fall-out from the Boko Haram conflict or Nigerians could face the consequences for years to come.
"We have to put out the fire in 18 months in northeast Nigeria. If we don't succeed in putting out the fire in 18 months, the situation will become protracted and chronic," said UN’s humanitarian coordinator in the country, Edward Kallon.
He told journalists in Abuja, the federal capital territory, that lack of funds hindered some progress made last year, even though aid agencies ramped up operations.
A conference is being held in Norway's capital, Oslo, next week to attract donors for programmes in Nigeria and Cameroon, Chad and Niger, which have also suffered the consequences of insurgent attacks on parts of their territories.
Federal authorities in Nigeria have affirmed their plans to close the camps and return many of the internally displaced to their home towns and villages as soon as possible.
In the meantime, over one million IDPs have returned to their homes since August 2015, said Kallon.
But there have been concerns about what awaits them, with homes and businesses destroyed, and basic services and infrastructure lacking because of the fighting.
The UN this year wants to raise more than N500 billion to provide food, shelter, healthcare and education, after a disappointing 2016 which saw only 53 percent of funding met.
Another shortfall "will expose vulnerable children, women, girls and youths to risks the country may fail to deal with in the future", said Kallon.He added there is no quick-fix to helping the displaced, noting that some cases elsewhere in the world can take 10 years or longer to rehabilitate.