Jerome Taylor: Largely unnoticed, violent Islamist groups have been looking across the Sahara

Boko Haram's goals are still inherently local, but there are fears that more internationalist groups may seek to link up

The attacks on churchgoers in Nigeria yesterday will further inflame the already tense relationship between Muslims and Christians in Africa's most populous nation.

But they also point towards a worrying increase in violent Islamism across Saharan West Africa that threatens to destabilise an already fragile region.

With the world's attention focused on violent Islamism in Pakistan, Yemen and Somalia, the rise of militant networks across Saharan Africa has largely gone unchecked. Following a crackdown by the Algerian government that began in 2008, al-Qa'ida in the Islamic Maghreb (AQIM) has spread its influence south across the vast Sahara and into Mali, Mauritania and Niger.

An area of the world that once drew intrepid tourists to its desert landscapes has fast become a no-go area, with scores of kidnappings and executions of foreigners. There are at least five Europeans still held hostage by what are believed to be AQIM militants.

Sheltered by the Sahara – an area so vast that even well resourced forces would find it impossible to police – AQIM is determined to make further forays south and has set its sights on the 80 million Muslims living predominantly in Nigeria's northern provinces.

Boko Haram, the Islamist group that claimed responsibility for yesterday's attacks, began life as an indigenous insurgency with an intense hatred of Nigeria's Christian south that launched a violent campaign to install sharia law. Its goals are still inherently local. But there are fears that the more internationalist militant networks in the area are hoping to link up with Nigeria's most notorious Islamists.

No direct evidence tying Boko Haram to al-Qa'ida has been established. But senior AQIM leaders have previously released supportive statements praising their work while Abul Qaqa, a Boko Haram spokesman, claimed in November that his group had reached out to them and received assistance.

Any alliance between Nigerian and global Islamists would be a major cause for concern. Not only would it give Boko Haram legitimacy within international jihadist circles and access to significant finances and expertise. It would also create an arc of violent Islamists stretching from Somalia to Mali.