A German hostage kidnapped by Boko Haram in Nigeria six months ago has been freed after a military raid led by Cameroonian forces and their allies, Cameroon said Wednesday.

"A special operation led by Cameroonian armed forces along with security services of friendly nations succeeded this night in freeing Nitsch Eberhard Robert, a German citizen abducted in Nigeria in July 2014 by the Boko Haram sect," the presidency said in a statement.

A spokesman for the German foreign minstry confirmed the man's release, adding that he was now in Cameroon's capital Yaounde.

The announcement came as Nigeria and its neighbors were holding talks in Niamey on how to combat the militants, whose insurgency has left 13,000 dead and forced 1.5 million from their homes since 2009.

Boko Haram is stepping up attacks in Nigeria and neighboring countries, prompting Chad to send a convoy of troops and 400 military vehicles Saturday into Cameroon to battle the insurgents.

The African Union said Wednesday that defeating Nigeria's "dastardly" Boko Haram insurgents needed support from across the continent.

"Boko Haram is a threat not only to Nigeria and the region, but also to the continent as a whole," Nkosazana Dlamini-Zuma said in a statement.

Global outrage has been building since Boko Haram's massive January 3 attack on the Nigerian border town of Baga, feared to be the worst in the militants' six-year insurgency.

Boko Haram leader Abubakar Shekau claimed responsibility for the assault which is thought to have killed hundreds, if not more.

In his 35-minute video message he said: "We will not stop. This is not much. You'll see."