When Ibrahim was nine Boko Haram militants chopped off his friend's hand and dipped the stump in boiling oil

When Ibrahim was nine years old, Boko Haram militants chopped off his friend's hand and dipped the stump in boiling oil.

Much of his family had been butchered by the group; when he was 11, he saw a jihadi shooting his father dead.

'When I think about Boko Haram I have no emotion,' he told MailOnline in Bikari camp in Maiduguri, the wartorn capital of Borno state in northeastern Nigeria. 'I don't think I feel anything any more.'

Ibrahim, 13, is just one of millions of Nigerians displaced by the savage nine-year insurgency, which has claimed over 20,000 lives, triggered malnutrition and disease, and forced entire communities to flee their homes.

Now there is a growing fear that the African terror organisation – parts of which are affiliated to ISIS – is threatening to spill into Europe along migrant routes.

MailOnline visited the city of Maiduguri, the war-torn capital of northeastern Borno state, to see first-hand the scale of the disaster. We travelled with the British charity Street Child, one of a small number of NGOs that helps children caught up in the conflict.

Nigeria was the third biggest source of illegal migration into Europe last year with 37,000 new arrivals, behind only Syria and Afghanistan and ahead of Iraq by 10,000.

Last month, a hardened Boko Haram fighter who had admitted slaughtering schoolchildren, burning down churches and taking girls hostage, was arrested by German police in Munich.

MailOnline visited the city of Maiduguri, the war-torn capital of northeastern Borno state, to see first-hand the scale of the disaster. Pictured: Beggar boys known as Almajiri at the Goni Habeb Sangaya school in downtown Maiduguri

We travelled with the British charity Street Child, one of a small number of NGOs that helps children caught up in the conflict. Pictured: Children beg by the roadside

Boys study maths at Street Child's Jajeri Bayan Texaco school in Maiduguri

So far, most Nigerian migrants have come from parts of the country free from the terrorist threat. But if the terror group is not suppressed, experts believe that a new surge in migration to Europe may be on the way – with more terrorists hiding in its ranks.

Fatima Akilu, a former NHS psychologist who leads Nigeria's de-radicalisation programme, told MailOnline: 'As Boko Haram gets squeezed in Nigeria by the military, what is the next stage? Embed themselves in other countries far from their homeland? That could be the plan.'

Maiduguri's population has doubled to two million with an influx of people fleeing the group, which seeks to establish a caliphate in the northeast, as well as parts of neighbouring Cameroon, Chad and Niger.

In the city's largest camp, Dalori, we captured drone footage to illustrate the magnitude of the staggering humanitarian emergency.

In the city's largest camp, Dalori, we captured drone footage to illustrate the magnitude of the staggering humanitarian emergency

More than 50,000 traumatised refugees in the Dalori camp's two sections could be seen living in fear and deprivation beside open sewers

An aerial view of Dalori camp, Maiduguri, the largest in Nigeria

Former Boko Haram child soldiers at Bakasi refugee camp, Maiduguri

More than 50,000 traumatised refugees in the camp's two sections could be seen living in fear and deprivation beside open sewers.

The camp is poorly defended and close to jihadi areas, making it a prime target for terrorists. Attacks take place with gruesome regularity.

Two weeks ago, a suicide bomber infiltrated the camp and killed five people, including a 60-year-old man and his nine-year-old son.

'The refugees are living here in fear, like hunted animals,' said head of security Baba Shehu, 51, who ferried the dead and wounded to hospital in a wheelbarrow in the aftermath of the atrocity.

A child separated from his parents at a Street Child facility at Jajeri Bayan Texaco school

Standing at the scene of the blast, Mr Shehu described how the horror unfolded. 'A car pulled up at the gates and two women got out,' he said. 'When the security guards questioned them, they began to run.'

The first woman stumbled, he said, causing her bomb to detonate. It killed her but nobody else was hurt. The second attacker ran towards the camp.

'We saw in the light of the explosion that she was climbing a pile of refuse, trying to get in,' he said.

'She jumped over the wall, rushed to a group of people and fell inside them. The bomb went off and her head flew upwards into a tree. There were bodies and screaming people everywhere.'

More than 626,000 displaced people live in 180 squalid camps like Dalori, with over 6,700 new arrivals in a week. Many of the younger generation have now begun to dream of a new life in Europe.

'Of course the youth wants to leave here and go to the EU,' said Abdul Hamid, a social worker in the Bakasi camp. 'The only thing that stops them is the money.'

Last week, a village less than half a mile from the camp was razed to the ground by militants, leaving at least three dead and seven injured, as well as the loss of 57 homes.

This is business as usual in Maiduguri, which saw the highest concentration of fatalities in the country last year. In January, 12 people were killed and 48 injured in a double suicide bombing at the market downtown.

The streets are dotted with armoured cars which train their guns on thousands of yellow 'KK' tuk-tuks. Motorcycles, the terror group's favoured method of transportation, have been banned and a defensive trench has been dug at the city's edge. The push factors are obvious.

The streets are dotted with armoured cars which train their guns on thousands of yellow 'KK' tuk-tuks. Motorcycles, Boko Haram's favoured method of transportation, have been banned and a defensive trench has been dug at the city's edge

Sergeant Abdullah guards the gates of Dalori camp, Maiduguri, the largest in Nigeria, which is frequently attacked by Boko Haram

A single armoured car protects the gates to Dalori camp, Maiduguri, one of Boko Haram's prime targets

Children and young people, who are more likely to journey to Europe, have been particularly affected by the crisis. Boko Haram – which achieved international notoriety in 2014 when it kidnapped 276 Chibok girls – has been known to use those as young as five to carry out its brutal suicide attacks.

It is also known for its child soldiers. Youngsters who have escaped the group comprise some of the the most traumatised refugees in the camps.

Several former child jihadis in Bakasi camp gave a harrowing account of life inside the terror organisation, describing an Islamist cult of brainwashing, torture and beheadings.

Ibrahim, 13, was seized from his family at the age of nine and forced to read the Koran day after day for months while a boy of his own age beat him with the butt of an AK-47.

Eventually, he was given a gun of his own and welcomed into the terror group. Ironically, he was appointed jailer, replacing the boy who had beaten him so brutally before.

'My mother was crying and crying when they took me,' he said. 'I never felt 100 per cent Boko Haram. Every night we went to sleep hungry and we pounded leaves to eat.'

He was rescued during a gunfight with a group of traditional hunters who have been fighting the jihadis.

'They forced me to put down my AK,' he said. 'Then a man took my hand and I realised it was my father fighting for me and I was safe.'

Tragically, however, his relief was shortlived. 'The shooting started again and my father was hit in the head,' he said. 'The bullet went into one temple and came out the other side. I saw him die.'

Ibrahim is part of a group of former Boko Haram members who are often shunned by society when they return, and are dreaming of a life in the West. There are about 300 such children and teenagers in the Bakasi camp, which has an overall population of 21,000.

Hassan, 15, had 21 siblings before the insurgency. Only five of them are alive today. His entire family was forcibly recruited by Boko Haram and after a period of brainwashing, he too became infatuated with the terror group.

'I saw a lot of people getting killed but I was never selected for an operation,' he said. 'I wanted to be selected. It would give me pride, I loved it.

'I liked the Amirs (leaders), I saw them as good people. I wanted them to like me so I would be selected for an operation.'

Former Boko Haram child soldier Hassan at Bakasi refugee camp, Maiduguri. Hassan, 15, had 21 siblings before the insurgency. Only five of them are alive today. His entire family was forcibly recruited by Boko Haram and after a period of brainwashing, he too became infatuated with the terror group

Hassan, pictured at the Bakasi refugee camp, Maiduguri, added: 'I wanted to be selected. It would give me pride, I loved it. 'I liked the Amirs (leaders), I saw them as good people. I wanted them to like me so I would be selected for an operation.'

After two years, his father confided that he wanted to run away. Hassan decided to go with him, together with his brother, mother and aunt. The rest of the family refused.

They were pursued, however, by his 13-year-old cousin who caught them up on a bicycle. He shot the women dead, while the men – who were further up the road – managed to escape.

Experts fear that if these traumatised children find their way to Europe as migrants, they would be in serious danger of re-radicalisation.

'This is absolutely a risk,' said Fatima Akilu. 'In Nigeria I run a comprehensive de-radicalisation programme that covers ideology, livelihood and education. But we don't have the resources to reach many of the children in the camps, and they certainly wouldn't get it in Europe.'

A major Nigerian military offensive codenamed Deep Punch pushed the terror group out of urban areas last year and won territorial gains.

In response, Boko Haram has ghosted into more remote locations and is focusing on soft targets, with an increased use of suicide bombs in Maiduguri.

Yet with an eye on the upcoming elections, the country's president, Muhammadu Buhari, bizarrely declared that the terrorists had been 'defeated'.

His words rang hollow on Wednesday, when Boko Haram released a 10-minute video of their leader, Abubakar Shekau, taunting the army and calling himself 'invincible'. He also claimed to be holding wives of policemen as hostages.

Analysts agree that Boko Haram has indeed lost some ground. But contrary to Mr Buhari's claims, BBC research shows that the number of people slaughtered by the jihadi organisation actually increased last year.

'Every time the Nigerian government declares victory, it loses credibility,' Grant T Harris, formerly President Obama's senior adviser on Africa, told MailOnline.

'Any claim that Boko Haram has been defeated is incredulous. The war will become all the more political in the run-up to the Nigerian election. In turn, Boko Haram will try to prove it is a salient and capable force by mounting fresh attacks.'

Mr Harris, now CEO of Harris Africa Partners, added: 'I don't see any quick resolution. We have a long way to go to truly cut off Boko Haram's resources and stifle its recruitment. This can only be done with a humanitarian programme to encourage development alongside the military response.'

Some children displaced by Boko Haram have found their way into Islamic madrassas in the city, which teach them the Koran and send them out into the streets to beg.

Known as 'Almajiri' children – meaning 'itinerant youngsters under Koranic instruction' – they constitute the largest group of out-of-school children in Nigeria.

Goni Usman, 50, head of the Goni Habeb Sangaya school in downtown Maiduguri.

At the Goni Habeb Sangaya school in downtown Maiduguri, MailOnline visited a dirty, squalid and windowless room measuring about 15 sq ft which served as a bedroom for 20 child beggars.

'Our children study the Koran for one-and-a-half hours, then we send them begging for two-and-a-half hours,' said the head imam, Goni Usman, 50.

'They have to pay for their tuition somehow. We used to have them farm during the rainy season to generate money for the school, but we have not been able to do this for seven years because of the conflict.'

Boko Haram has killed more than 2,295 teachers and displaced 19,000 since the insurgency began in 2009. When the new term began last September, more than 57 per cent of schools in Borno state remained closed.

According to the UN, over three million Nigerian children are in need of emergency education support. Street Child currently provides learning facilities for 23,000, in the hope that foreign aid efforts may help to some extent to alleviate the crisis.

The luckier children can be seen every day on the streets of Maiduguri in colourful school uniforms, and a few NGOs like Street Child are helping to provide an education to the most deprived children, including the Almajiri.

At the Jajeri Bayan Texaco school set up by the charity, hundreds of orphans and children who lost their parents as a result of the insurgency are provided with a Western-style education.

At the Jajeri Bayan Texaco school set up by the charity, hundreds of orphans and children who lost their parents as a result of the insurgency are provided with a Western-style education. Pictured: A girl separated from her parents playfully salutes at a Street Child facility

The school lies a short distance from the ruins of a house that belonged to the Boko Haram leader, Abubakar Shekau, who was using it to plan an attack when it was destroyed by the army. A girl there separated from her parents playfully salutes for the camera

A girl separated from her parents cares for a baby at a Street Child facility at Jajeri Bayan Texaco school

The school lies a short distance from the ruins of a house that belonged to the Boko Haram leader, Abubakar Shekau, who was using it to plan an attack when it was destroyed by the army.

Other initiatives are also in force, such as a seed finance programme that provides a small sum of money to female heads of families so that they can set up their own small businesses.

As things stand, however, both military and humanitarian resources are insufficient to remedy the huge crisis – which may soon arrive on Europe's doorstep.

Last April, Nigeria's chief humanitarian coordinator, Ayoade Alakija, warned: 'The world could see a mass exodus from a country of 180million people if support is not given, and fast.'

Fatima Akilu agreed. 'This is a strong possibility,' she said.

'At the moment, people still trust that the Government will resolve the problem. But if they lose all hope of returning to their homes, they may very well be triggered to leave.'

She added: 'As Boko Haram comes under military pressure, it will no longer see itself as attached to Nigeria, but more connected to other parts of the world through ISIS.

'We already know that Boko Haram cooperates with other groups and fights with ISIS in a variety of countries. Europe could be the logical next step.'

Street Child's latest appeal, Right to Learn, will support 10,000 children across Nigeria, Sierra Leone and Liberia to go to school and learn. Through UK Aid Match, the UK government are matching all donations, pound for pound, until 15th February. To donate, visit: street-child.co.uk