LAGOS, Nigeria (AP) — Increasing atrocities by extremists and uncontrolled reprisals by security forces have killed at least 1,500 people this year in northeastern Nigeria's Islamic uprising, Amnesty International reported Monday, accusing both sides of war crimes and crimes against humanity.
In a new report, the London-based advocacy group called for an international investigation.
"The international community cannot continue to look the other way in the face of extrajudicial executions, attacks on civilians and other crimes under international law being committed on a mass scale," said Netsanet Belay, the group's advocacy director for Africa.
The report said the toll of more than 1,500 deaths indicated "an alarming deterioration." That would equal the total number of people killed since the uprising began in 2010 through June 2013, according to an Associated Press count.
The extremists struck again Sunday night, burning down the military quarters and destroying a cellular telephone tower in Ngelzarma town, Yobe state. Resident Abdullahi Umaru said the militants killed three police officers and two soldiers.
He said residents were fleeing Monday morning, fearing another attack by extremists and harassment by security forces.
This year started turbulently for the military, with President Goodluck Jonathan firing all his service chiefs and then replacing the defense minister last month, amid growing anger at the military's inability to curb the killings. Three northeastern states covering one-sixth of the country have been under a military state of emergency since May last year.
Amnesty International said more than half of those killed this year have been civilians slaughtered by extremists. They include scores of students who were gunned down in schools, had their throats slit or were burned alive in locked dormitories set aflame while they slept.
Nearly all the other deaths involve soldiers gunning down unarmed detainees freed in a March 14 attack on Giwa military barracks in Maiduguri city, the report said.
It said Amnesty has witnesses and satellite imagery indicating more than 600 people were killed that day. It was the bloodiest day on record in the 4-year-old uprising. Hospital workers told the AP they counted 425 corpses, which had to be buried in a mass grave because there was no space in the mortuary.
But the Amnesty report says satellite imagery indicates there are three mass graves.
The report described what happened when soldiers came upon 56 unarmed detainees hiding in a classroom of the University of Maiduguri after they were freed.
"We watched as the soldiers opened fire killing all 56. They were killed in front of us. All of them," the report said, quoting an unidentified witness.
In another instance, the report said vigilantes rounded up 198 freed detainees and turned them over to soldiers who, after a brief argument with the vigilantes, forced the detainees to lie down on the ground and gunned them down.
Such killings follow "an entrenched pattern of deaths in custody" in northeast Nigeria, Amnesty said.
Giwa army barracks holds a notorious detention center where people have been held illegally for months without being charged or allowed access to lawyers or families. An AP investigation of hospital mortuary records found more than 3,300 detainees died there between January and August last year in extrajudicial killings, from untreated wounds from beatings and from starvation and suffocation in overcrowded cells.
Monday's report calls for the United Nations to help investigate "given Nigeria's apparent unwillingness and inability to investigate and prosecute perpetrators of these crimes."
Associated Press writer Adamu Adamu contributed to this report from Damaturu, Nigeria.