The Cameroonian Army, one of the key forces in the coalition against the militant group Boko Haram, has killed 100 fighters from the Islamic State-linked organisation, and freed 900 hostages.

Agence France-Presse reported the numbers of killed and freed, citing Cameroon government officials. Cameroon has been facing almost daily attacks from Boko Haram as the number of suicide bombings, often carried out by young women recruited in Nigeria, increases in the far north of the country.

Who are Nigeria's Boko Haram terrorists? Boko Haram 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.

Overnight a double suicide bombing by Boko Haram in Waza in the north killed at least three. Security sources told Reuters that as many as six could have been killed in the twin blasts. A third suicide bomber was killed by security forces before she was able to detonate her device.

Niger, Chad and Cameroon and have all been helping Nigeria retake territory lost to Boko Haram after the group began carrying out cross-border attacks beyond its heartland in northern Nigeria.

The 8,700-strong regional task force has stalled in its operations, however, as the national armies appear to be battling Boko Haram independently with little collaboration.

While Chad, Cameroon and Niger have, for the most part, remained within their own territories to contain the Boko Haram threat, in March around 200 vehicles crossed into north-east Nigeria to open a new front against the group.