UN Resident and Humanitarian Coordinator said women and young girls are the most affected by the ongoing war.
The United Nations on Thursday appealed for $1.3 billion to provide assistance to six million Nigerians who are suffering the impact of a long-running Islamist insurgency in the northeast region of the country.
Aid agencies said militant Boko Haram group and its offshoot, Islamic State West Africa Province, have been fighting Nigerian security forces in northeast Nigeria for over a decade, displacing more than 2 million people and killing hundreds of others.
Matthias Schmale, the UN Resident and Humanitarian Coordinator for Nigeria said the "large-scale humanitarian and protection crisis shows no sign of abating".
The UN said the number of children suffering from acute malnutrition was projected to increase to 2 million this year, up from last year’s 1.74 million.
"Women and young girls are hit the hardest," Schmale said when launching the financial appeal in North-eastern Adamawa state of Nigeria.
He said more than 80 per cent of people mainly women and children, were in need of aid across the states Borno, Adamawa and Yobe.
"They face increased risks of violence, abduction, rape and abuse," he said.
Nigeria's Government says it is winning the fight against insurgents and that some areas have now been cleared of militants and are safe for villagers to return.