Nigeria Army is replacing the military commander of the fight against Boko Haram after half a year following a string of insurgency attacks despite years of official claims the group has almost been defeated, military sources said on Wednesday.

The shake-up underscores the fragility of the security situation in Nigeria's northeast, where the conflict with the Islamist insurgent group is now in its ninth year, despite assertions by President Muhammadu Buhari's administration that it is on its last legs.

Ibrahim Attahiru, theatre commander of the operation against Boko Haram, is being replaced by Major General Rogers Nicholas in the wake of a series of "embarrassing" attacks, two military sources said.

They said the conduct of the war against the insurgents is now being reviewed.

The attacks, that occurred during Attahiru's command, include the kidnapping of members of an oil prospecting team which led to at least 37 people being killed in July, and deadly assaults on the towns of Magumeri, Biu and Madagali, the sources said.

A military spokesman declined to comment on the replacement of Attahiru. A spokesman for the president, who serves as Nigeria's commander-in-chief, also declined to comment.

Governor of Borno state, which is at the epicentre of the insurgency, has said the government's long-term plan now is to corral civilians inside fortified garrison towns - effectively ceding the countryside to Boko Haram.

That plan and the spate of deadly attacks have raised questions about assertions by the government and military that Boko Haram has been all but wiped out, as well as doubts about Nigeria's ability to retain sovereign integrity in the northeast.

Reuters