An Amnesty International report has accused the Nigerian military of the murder of more than 8,000 people and demanded an immediate investigation into military commanders for possible war crimes.

The Report, released on Wednesday, alleged that more than 7,000 young men and boys were starved, suffocated and tortured to death in military detention from 2011. The report, based on hundreds of interviews and leaked military documents, also revealed that more than 1,200 people were unlawfully executed since February 2012.

"This sickening evidence exposes how thousands of young men and boys have been arbitrarily arrested and deliberately killed or left to die in detention in the most horrific conditions. It provides strong grounds for investigations into the possible criminal responsibility of members of the military, including those at the highest levels," Amnesty International's Secretary General Salil Shetty said in a statement.

Amnesty International called for the immediate investigation on present and past military commanders for possible war crimes and crimes against humanity committed by the Nigerian military in the course of the fight against Boko Haram in the north-east of the country.

"Whilst an urgent and impartial investigation of these war crimes is vital, this report is not just about the criminal responsibility of individuals. It is also about the responsibility of Nigeria's leadership to act decisively to end the pervasive culture of impunity within the armed forces," Shetty said.

The report listed nine former and present top military commanders including Major Gen. John A.H. Ewansiha, Major Gen. Obida T Ethnan, Major Gen. Ahmadu Mohammed, Brigadier Gen. Austin O. Edokpayi and Brigadier Gen. Rufus O. Bamigboye, the Associated Press reported.

However, the Nigerian military rejected the report as "blackmail," claiming its factual materials were given by "disgruntled elements."

"The Nigerian military ... rejects the biased and concocted report provided by Amnesty International," Major Gen. Chris Olukolade said in a statement, according to Reuters. "The Nigerian military does not encourage or condone abuse of human rights, neither will any proven case be left unpunished." 

Nigerian President Muhammadu Buhari responded to the allegations on Wednesday, saying that he will review Amnesty's findings, The Premium Times Nigeria reported. He added that Nigerians need to know that "this administration will leave no stone unturned to promote the rule of law, and deal with all cases of human rights abuses,"