Reuters news agency obtained a video Sunday that reportedly shows Nigerian troops summarily executing captured members of the terrorist Islamic group Boko Haram.
But Colonel Mohammed Yerima, a Nigerian army spokesman, has denied that report, telling Reuters the video is fake.
"How can they do that? It is not possible. This is the Boko Haram tactics," he said. "They will do the killing, say it's the military and then Amnesty International and so on will blame us. It's not possible for Nigerian troops to act in this way."
The video comes weeks after Amnesty International released a report entitled "Nigeria: Trapped in the cycle of violence," which strongly criticized government tactics against Boko Haram (the name roughly means "Western education is sinful").
"The cycle of attack and counter-attack has been marked by unlawful violence on both sides, with devastating consequences for the human rights of those trapped in the middle," said Salil Shetty, secretary-general of Amnesty International.
Admiral Ola Ibrahim, Nigeria's chief of defense staff, commented on the report to the BBC last week, saying:
"We have rules of engagement. A few of our men who have violated some of these rules are on trial."
He added, "The information technology and present-day capacity to manipulate even pictures and use it to your advantage is part of the kind of warfare that we are acutely aware of."
In early November there were reports of the Nigerian army killing between 30 and 40 young men in raids in the northeast city of Maiduguri, a known Boko Haram stronghold. It was suggested many were not armed or members of Boko Haram.