The Chadian government has announced it will send troops to Cameroon to help fight Nigerian terror group Boko Haram's insurgency.

The announcement came a few days after Cameroonian troops said they killed some 143 Boko Haram fighters after they ambushed a military camp in Kolofata, some 1,200km from the capital Yaoundé.

Who are Boko Haram militants?

Boko Haram, which fights against Western influence in Nigeria and aims to impose its version of sharia law in the country, declared an Islamic caliphate in Gwoza, along the Cameroon border, in August 2014.

The group has been raiding several cities in the north of the country in a bid to take control of more land.

Violence linked to Boko Haram's insurgency has resulted in an estimated 10,000 deaths between 2002 and 2013.

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

Cameroon's President Paul Biya said in a statement: "[Chad President Idriss Deby Itno] has decided to send a large contingent of Chadian armed forces to help the Cameroonian Armed Forces facing... repeated attacks from the Boko Haram terrorist sect".

It is not clear yet how many troops Chad will send to Cameroon, Reuters reported.

Boko Haram members attack towns and villages mainly in central and northern Nigeria, along the border with Cameroon, where they have also established an Islamic caliphate.

The group sometimes crosses the Nigerian border and carries out attack in Cameroon, where last September soldiers killed 100 insurgents who attempted to attack a town.

The terrorists, condemned worldwide for kidnapping 220 schoolgirls last April, captured 16 towns at the beginning of January and slaughtered at least 2,000 people, including women and children, in Baga town, Borno state.

The mass-killing was dubbed "possibly the deadliest" committed by the terrorists, believed to have murdered thousand of civilians since their insurgence began in 2009.

Boko Haram
Images of before and after the attack on Baga, North Eastern Nigeria. First taken on 2 January 2015. Many thatch roof structures are visible. These have been rebuilt since the attack on Baga in April 2013. Second image of Baga taken on 7 January which show many of the thatch roof structures have been razed. The dark colour represents burned areas, while the read indicates healthy vegetation DigitalGlobe