More than half schools in the state at the epicentre of Nigeria's conflict with Boko Haram are still closed, United Nations' children agency said on Friday, as the insurgency drags into its ninth year.

The lack of schools could continue to fuel Boko Haram or similar movements in the future. Poor education for Nigeria's restive northeastern youth left them with few prospects, driving them to join the Islamist insurgency, experts say.

The conflict has killed more than 20,000 people since 2009 and embroiled the region in one of the world's worst humanitarian crises, with at least 10.7 million people in need of assistance, according to United Nations.

"In addition to devastating malnutrition, violence and an outbreak of cholera, the attacks on schools is in danger of creating a lost generation of children, threatening their and the countries future," Justin Forsyth, a deputy director for United Nations Children's Fund (UNICEF), said in a statement.

Over 57 percent of schools are shut in Borno state, where most of the conflict and resulting crisis have taken place, as the new school year begins, the statement said.

More than 2,295 teachers have been killed, at least 19,000 displaced and almost 1,400 schools destroyed, UNICEF said.

Despite aid agencies' efforts to set up schools for children in the northeast, particularly those displaced by the insurgency, UNICEF said it has only received three-fifths of the total funding it needs for 2017.

Combined with climate change taking its toll in recent years on farming, a mainstay of the region, the lack of schooling has left many without job opportunities.

Nigeria's northeast has been plagued by poor education for decades.

British colonialisation in the 19th and first half of the 20th century ushered in priests who set up schools in the country's south, which came to be religiously dominated by Christianity.

The partly autonomous northern regions, governed by Muslim rulers under Britain, saw fewer similar attempts, and, by 1950, northern Nigeria had produced one university graduate.

Reuters