Nigerian authorities have arrested a "key figure" in relation to the abduction of over 200 schoolgirls in Chibok, Borno state on April 14.

Christian Solidarity Worldwide (CSW) reports that the military arrested a businessman named Babuji Ya'ari - known to be a Boko Haram ringleader - along with two female operatives who work for the extremist group, this week.

In addition to leading a violent Boko Haram cell, Ya'ari is said to have "participated actively" in the abductions of April 14 that resulted in global outrage and an international campaign to bring the girls to safety. 219 of the young women, mostly aged between 16 and 18, however, are still missing - sparking fears that they have been sold into slavery.

"Babuji Ya'ari has been coordinating several deadly attacks in Maiduguri since 2011, including the daring attacks on customs and military locations as well as the planting of IEDs [improvised explosive devices] in several locations in the town," a defence ministry spokesman has said in a statement.

A deadly bomb ripped through a market in Maiduguri just hours after Nigerian officials announced Ya'ari's arrest, killing at least 18.

His detention has been described as a "breakthrough" in the wake of increasing violence across Nigeria, though The Guardian has warned that it may not be as significant as many hope. "Nigeria's military often claims arrests...[but] often, no further public information is provided once arrests have been made, and suspects rarely stand trial," the newspaper notes.

The Nigerian government has faced criticism for its failure to stop the insurgents, and President Goodluck Jonathan is under increased pressure to regain control against Islamic extremists. He declared a state of emergency in Muslim-majority Adamawa, Borno and Yobe states in May 2013 and has authorised an increased military presence across the country, but the violence continues.

In response to these latest developments, Chief Executive of CSW Mervyn Thomas has released a statement expressing the need for further sanctions. "We extend our heartfelt condolences to the many families bereaved during the series of attacks across the country," he says.

"In Borno in particular, the targeting of the Christian community is tantamount to religious cleansing and violates the right to freedom of religion or belief, as enshrined in article 38 of Nigeria's federal constitution.

"While we greatly commend the Nigerian military for the breakthrough in the Chibok case and for making steady inroads into the terrorist network, we also renew our call for effective protection for civilians, particularly in southern Borno and southern Kaduna, so they can go about their daily lives without the threat of violence or death."