Nigerian security forces have committed massive rights violations including summary executions in trying to crush the insurgency by the Islamist extremist group Boko Haram, Amnesty International said Thursday.
In a report, the London based rights groups charged Nigeria's military with carrying out extra-judicial killings and showing "little regard for the rule of law or human rights" in its campaign against Boko Haram.
"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, Amnesty's secretary general.
Violence linked to the Boko Haram insurgency is believed to have left more than 2,800 people dead since 2009, including killings by security forces.
Nigeria has deployed special military units to several areas hit hardest by the group, including the northeastern city of Maiduguri, considered the Islamists' base.
"Amnesty International received consistent accounts of witnesses who saw people summarily executed outside their homes, shot dead during operations, after arrest, or beaten to death in detention or in the street by security forces in Maiduguri," the rights group said.
"Witnesses interviewed by Amnesty International described seeing people who were clearly no threat to life, unarmed, lying down or with their hands over their head or cooperating shot at close range by the security forces," the report further said.
Residents of Maiduguri have previously accused soldiers of firing on by-standers after suspected Boko Haram attacks, although the military has consistently denied wrongdoing.
Lieutenant Colonel Sagir Musa, the military spokesman in Maiduguri, told AFP he was not yet familiar with Amnesty's allegations and would respond later Thursday.
The rights group said Boko Haram's relentless targeting of civilians "may constitute crimes against humanity," but urged Nigeria "to take responsibility for its own failings" in its campaign against the insurgents, who have said they want to create an Islamic state in the north.
President Goodluck Jonathan has faced intense criticism over what some term his failure to stop the killings.
Oil-rich Nigeria, Africa's most populous country, is roughly divided between a mainly north and mostly Christian south.