Nigeria has stopped thousands of citizens from leaving the country to prevent them from joining terror groups or being lured into prostitution and slavery. The Nigeria Immigration Service (NIS) said it stopped some 24,000 people from leaving the African nation between January 2014 and March 2015 following increasing reports of Nigerians participating in terror activities in North Africa and the Middle East.

"What the NIS is doing is barring young Nigerians with doubtful intentions from leaving our shores," NIS spokesperson Chukwuemaka Obuah was quoted by PRNigeria as saying. "Before the advent of Isis [Islamic State], the NIS has been battling with illegal migration, organised or otherwise. The push and pull factors have always been there and the NIS has fashioned a robust profiling mechanism that identifies those whose intent for going abroad is either inimical to themselves or the image of the country."

Obuah added that several people are motivated to join terrorism because they are unemployed. "We have always had problems of Nigerians going abroad for greener pasture. We look at the age of the intended traveller and the person he is travelling with, put them by the side and profile them thoroughly," he added.

Who are Nigeria's Boko Haram terrorists?

Boko Haram (recently renamed Iswap) fights against Western influence in Nigeria and aims to impose its version of Sharia law in the country.

The group declared an Islamic caliphate in Gwoza, along the Cameroon border, in August 2014.

Boko Haram has raided several cities in the north of the country in a bid to take control of more land.

Three states − Adamawa, Borno and Yobe − have been under a state of emergency since May 2013, due to Boko Haram's attacks.

The group has killed more than 3,000 people since the beginning of 2015.

Nigerian terror group Boko Haram, which has killed thousands across northern Nigeria since its insurgence became violent in 2009, has pledged alliance to IS, which controls large swathes of Syria and Iraq. Following the alliance between the two Islamist giants, analysts warned that people willing to join IS are now travelling through Nigeria.

David Otto, chief executive of UK-based TGS Intelligence Consultants, told IBTimes UK that Boko Haram declared its allegiance to IS in a bid to boost its credibility, recruitment and power.

"The original Boko Haram has been advocating for a caliphate in the regions of northern Nigeria, northern Cameroon, part of Niger and part of Chad. This is where the original Bornu empire used to be located," Otto told IBTimes UK. "Boko Haram allied with IS, which speaks about having a caliphate in some parts of Iraq, Libya and Syria. The allegiance is a good opportunity for them not just in terms of sharing the same ideology, but also in terms of sharing loots, recruitment and motivation."

Otto warned that the West should pay more attention to this allegiance as it means that people willing to join IS will travel through Nigeria to reach Libya and then Europe.

"Young people who are motivated to go to IS – and who cannot join them through Turkey because of security services in the West – will find it very easy to join Boko Haram," he said. "These guys will easily travel from northern Nigeria, northern Cameroon, Chad and Niger to Libya because Libya is an open route. This area [west and central Africa] has been ignored by the West as it believes it is not that much of a threat. But this is more of a threat than Turkey."

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