Boko Haram continues to commit "horrendous acts against civilians", said the head of the United Nations office in West Africa.
Speaking to the UN Security Council via video conference from Abuja, Mohammed Ibn Chambas, the special representative of the secretary-general and head of the United Nations Office for West Africa, said: "We've received reports that children, in particular, have been abducted, abused, recruited, maimed and killed.
"Schools in north-east Nigeria are no longer safe places of learning, as many of them continue to be attacked, looted and destroyed. Several schools in the areas targeted by Boko Haram in Cameroon and Niger also remain closed."
Boko Haram is in the midst of a bloody six-year-old campaign to carve out an Islamic state in religiously mixed Nigeria.
"Boko Haram's recent allegiance to the Islamic State of Iraq and the Levant, whether for publicity reasons or to tap into ISIL's support, is also a concern as it gives a clear signal that Boko Haram's agenda goes well beyond Nigeria," Chambas added.
Speaking to the council about the humanitarian impact of Boko Haram continued violence, assistant secretary-general for humanitarian affairs and deputy emergency relief coordinator Kyung-Wha Kang said: "The conflict has caused death and injury on a large scale, destroyed homes and infrastructure. More than 7,300 civilians have been killed by Boko Haram since the beginning of 2014 in the three state of emergency states.
"This year alone, 1,000 people have lost their lives. More than 300 schools have been severely damaged or destroyed. Less than 40% of health facilities in affected areas remain operational. Gross human rights violations, including sexual and gender-based violence and child trafficking, are frequently reported.
"The escalation of Boko Haram-related violence in the region continues to hinder access to people in desperate need of humanitarian assistance and is limiting the scope of our response."
Kang added: "The humanitarian response in north-eastern Nigeria remains overall poor and fragmented," and she appealed for "additional funding to address the acute humanitarian needs of those affected by the conflict".
Recently, Nigeria's armed forces and troops from neighbouring Chad, Niger and Cameroon have driven Boko Haram from most positions it controlled earlier in 2015, reversing militant gains that forced Nigeria to postpone a 14 February election until 28 March.
Results from the election, potentially the closest contest since the end of military rule in 1999, were due to start trickling in on 30 March.
The Security Council is negotiating a resolution - drafted by Chad, Angola and Nigeria - to back and fund a regional force to take on Boko Haram. The 54-nation African Union has already approved a force of 10,000 troops.