At least 400,000 children are now at risk of starvation in Nigeria's north-eastern states of Borno, Adamawa and Yobe, the United Nations has warned. North-eastern Nigeria has been ravaged by a seven-year-long insurgency by Boko Haram terror group, the International Business Times reports.

The UN defined the ongoing humanitarian emergency as the biggest crisis facing Africa today, with 75,000 children at risk of imminent death.

Boko Haram started carrying out attacks in Borno in 2009. However, the conflict soon spilled over into neighbouring states Cameroon, Chad and Niger.

The group is today blamed for the death of at least 20,000 people and the displacement of millions in the Lake Chad region.

The region, one of the poorest areas of the world, is witnessing a deep humanitarian crisis exacerbated by the negative effects of climate change. At present, at least 2.6 million people have been displaced by Boko Haram and at least 6.3 million people are facing hunger and potential starvation.

People are displaced from their farms and away from the lake and, due to security concerns, markets have been closed in areas at risk of attacks. This has led to food shortages and mass-starvation.