Soldiers of Niger and Chad discovered the corpses – many of them beheaded – dumped near a bridge near Damasak in the north of the country.
Witnesses described the findings as slightly “mummified” from the dry conditions suggesting the killings has taken place some time ago.
A military source confirmed: “Niger and Chad’s troops have discovered a mass grave at Damasak, which appears to contain the bodies of Boko Haram’s victims.”
The town had only just been liberated on Saturday from muslim extremist group Boko Haram – who have struck fear into the nation with it’s ruthless massacres of innocent civilians.
The group – who were responsible for the kidnapping of 276 Nigerian schoolgirls in April 2014 – has killed more than 5,000 people from 2009 to 2014 Around 20 local government areas in Nigeria, a territory the size of Belgium, have been controlled by the rebels as Africa’s largest populated nation continues to be overrun.
With the help of foreign allies, Nigeria’s army said on Tuesday it has pushed the rebels out of all but three districts.
President Goodluck Jonathan has been highly criticised for not doing enough to tackle the insurgents.