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 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.

Nigeria up close: Check out our Flipboard magazine

Military offensive and inter-ministerial 'task force'

In addition to its own military operation Lafiya Dole, Nigeria is now leading a regional offensive – consisting of 8,700 troops from Nigeria, Niger, Chad, Cameroon and Benin – against Boko Haram.

The offensive has scored some successes, such as the recapture of key territories and the release of thousands of civilians held captive by the group.

Nigeria's President Muhammadu Buhari, who vowed that his administration would defeat Boko Haram – has repeatedly called for a global effort to tackle the humanitarian crisis in the Lake Chad water basin, which comprises Chad, Cameroon, Niger, and Nigeria – all areas affected by Boko Haram.

Earlier this year, Nigeria launched what it called an "inter-ministerial task force" to tackle the humanitarian crisis in the north-east of the country.

"Nigeria has been providing food support, reintegrated healthcare, shelter, psycho-social support and access to water and sanitation amenities for those in need. We are also engaging highly respected community and religious leaders to discourage vulnerable youth from being radicalised," Buhari said in September.

Nigeria Borno malnutrition Lake Chad
A young boy suffering from severe acute malnutrition lies on the ground at one of the Unicef nutrition clinics in the Muna informal settlement on the outskirts of Maiduguri, capital of Borno State, north-eastern Nigeria, 30 June 2016 Stefan Heunis/AFP