Amnesty International on Friday accused Nigeria’s army of killing hundreds of men; women and children from a minority Shiite Muslim sect last December.
The human rights group said more than 350 people were believed to have been unlawfully killed by the military between December 12 and 14 with an attempt to cover-up the crime.
However, the military has dismissed the report as hasty, one sided and biased, Reuters reports.
Amnesty’s report relates to events in the northern city of Zaria where the Nigerian army burned people alive, razed buildings and dumped victims’ bodies in mass graves.
The report contains satellite images that appeared to show the location of a mass grave.
An eye witness, Yusuf said soldiers set fire to a makeshift medical facility in the sect’s compound.
“It is clear that the military not only used unlawful and excessive force against men, women and children, unlawfully killing hundreds, but then made considerable efforts to try to cover-up these crimes,” said Netsanet Belay, an Amnesty director.
A 16-year-old schoolgirl, Zainab, told Amnesty International they were in school uniforms when her friend Nusaiba Abdullahi was shot in the forehead.
“We took her to a house where they treated the injured but before reaching the house, she already died.”
A 10-year-old boy who was shot in the leg told Amnesty International how his older brother was shot in the head as they tried to leave the compound. “We went out to try to shelter in a nearby house but we got shot.”
Last week, Amnesty called for an investigation after a Kaduna state official told an inquiry into the clashes that the military secretly buried 347 people in mass graves.
But Nigerian army spokesman, Sani Usman said the Amnesty report lacked credibility.
“It is a hasty, one-sided and biased report aimed at arriving at a predetermined objective,” he said.
Most of the tens of millions of Muslims in Nigeria are Sunni, including Boko Haram militants who have killed thousands in bombings and shootings, mainly in the northeast since 2009.
Africa’s most populous nation has around 180 million people, including several thousand Shiite Muslims whose movement was inspired by the 1976 Islamic Revolution.